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50 Best Freshwater Aquarium Fish: The Complete Species Guide

So you’re looking to get into freshwater fishkeeping…

First off, congratulations! Fishkeeping can be an amazing, enjoyable hobby. I have been keeping fish for nearly 15 years and still learn new things every day.

Secondly, you’re already off on the right foot by researching. Way too many people walk into the pet store with no previous knowledge and buy fish that they aren’t prepared to keep – only to have them die days later.

In this guide, we will walk you though a few of the best freshwater aquarium fish for beginners and experts alike, as well as how to set up your first fish tank the right way.

Use the quick links below fish quicker navigation if you please.

50 Best Freshwater Aquarium Fish Species

Here are a few of our favorite freshwater aquarium fish for beginners:

1. Cory Catfish

cory catfish

If you’ve read other articles on my blog, you’re probably aware that Cory Catfish are one of my all-time favorite freshwater aquarium fish. These bottom-dwelling catfish are one of the best community fish out there – they survive in a wide range of condition, get along with (nearly) every species, and are active and entertaining to watch.

Since Cory Catfish are schooling fish, so they should be kept in groups of at least 4-5. They are not picky eaters and should do fine on a mixture of flakes and pellets. Dried Bloodworms are also a great supplemental food that will keep your Cories happy and healthy.

Because of their docile nature, I recommend only keeping Cories with other peaceful species such as Tetras, Mollies, Loaches, Plecos, and Danios.

  • Care Level: Easy/Moderate
  • Temperament: Peaceful
  • Tank Size: 20 gallons for groups of 5

2. Guppies

fancy guppies

Fancy Guppies are one of the most popular freshwater aquarium fish out there – and for good reason! Their hardy nature, bright coloration, and ease-of-care makes them a great choice, even for first time aquarium owners.

Because of their small size, Guppies are fine in pretty small tanks – 10 gallons should be more than enough. That said, Guppies are also known to reproduce very fast. 5 can turn into 50 in no time, so make sure you have a plan for all of the fry.

In terms of care, Guppies are about as easy as they come. As long as your aquarium is set up correctly and you feed with a high quality flake food, raising a healthy school of guppies should be a piece of cake.

  • Care Level: Easy
  • Temperament: Peaceful
  • Tank Size: 10 gallons

3. Mollies

Molly Fish

Mollies are a hardy, easy-to-keep livebearer known for their wide range of colors. Much like Guppies, Mollies thrive in most conditions and reproduce extremely quickly. That said, they are a bit larger and require a little more room.

Mollies are an omnivorous species, so they will eat just about anything fed to them. Flakes, pellets, and frozen foods all work very well. Mollies are also available in tons of different variations and colors, so every new aquarist should be able to find a type that fits their tank well.

  • Care Level: Easy
  • Temperament: Peaceful
  • Tank Size: 10 gallons

4. Swordtails

Swordtail red color males in the dark

Often grouped with Guppies and Mollies, Swordtails are the final livebearer on our list – but with a unique twist. Male Swordtails are equip with an interesting “sword” protruding from their tails, giving them their name. This unique trait makes them a great attention grabber in any community aquarium.

Like most livebearers, Swordtails are easy to keep and thrive in a wide range of environments. If kept in groups, Swordtails will also reproduce very quickly. As a small and peaceful species, they should be kept with other community-friendly fish.

  • Care Level: Easy
  • Temperament: Peaceful
  • Tank Size: 10 gallons

5. Kuhli Loach

kuhli loach in aquarium

If you’re looking for something a little different, a Kuhli Loach might be the perfect freshwater aquarium fish for you. Though this species resembles an eel, it is actually not in the eel family at all.

Kuhli Loaches are most active at night, so don’t expect to see them too much during the day. That said, Kuhli Loaches are much more likely to be active during the day if they are kept in groups of 3-4.

Another reason that Kuhli Loaches make great beginner aquarium fish is because they stay small (especially when compared with other loach species). At 3-5″ max length, a group can be kept in a 20 gallon aquarium with no problems.

  • Care Level: Easy/Moderate
  • Temperament: Peaceful
  • Tank Size: 20 gallons

6. Neon Tetra

neon tetra

Neon Tetras are small, high-energy fish known for their bright colors and interesting schooling habits. If you’re looking to set up a lively, natural aquarium, Neon Tetras are the perfect choice.

Since Neons max out at around 1-1.5″, good size schools can be kept even in small tank. Personally, I like to stock 1 Neon Tetra per gallon of water. That said, 10 gallon tanks should only house 5-7 Tetras sinse water parameters tend to swing around a little more.

Neon Tetras are considered pretty easy to keep and can adapt to many types of water conditions. As long as your tank is stable able cycled properly, you shouldn’t have any problems keeping this species.

  • Care Level: Easy
  • Temperament: Peaceful
  • Tank Size: 10 gallons

7. Bristlenose Pleco

bristlenose pleco

The Bristlenose Pleco, often referred to as the Bushy Nose Pleco or Armored Catfish, is one of the most popular types of Pecostomus in the aquarium hobby. Despite its alien-like appearance, the Bristlenose Pleco is actually a great, peaceful addition to any community aquarium.

One great thing about the Bristlenose Pleco is that it stays relatively small compared to other Pleco species. At right under 5″, they should be kept in tanks of at least 30 gallons.

Because of their huge appetite for algae, Bristlenose Plecos do a great job at cleaning up aquariums. That said, aquarium owners should do supplemental feedings of algae wafers to keep their Bristlenose Plecos well fed and healthy.

8. Betta Fish

betta fish

Even if you have never owned an aquarium before, chances are you’ve heard of Betta fish. These popular freshwater aquarium fish are famous for their bright coloration, versatility, and spunky personalities.

Despite the common belief that Betta fish can live in tiny bowls, you should really never attempt to keep them in anything less that 5 gallons. Small bowl are not only cruel, but can also cut a Betta’s lifespan significantly. This list of the best Betta tanks is a great resource for housing a Betta the correct way.

Though Bettas usually prefer a tank to themselves, there are several other species that can co-habitat with them well. A few suitable Betta tank mates include Cory Catfish, Plecos, and certain Tetras.

  • Care Level: Easy
  • Temperament: Aggressive
  • Tank Size: 5 gallons

9. Zebra Danio

zebra danios

Zebra Danios are one of the most iconic beginner freshwater aquarium fish in the hobby. They are prized for their instantly recognizable striped pattern, energetic antics, and ease-of-care.

Zebra Danios are most energetic when kept in small schools – a group of 7-8 Danios will provide all the entertainment you need from a freshwater tank. Because they tend to be so zippy and lively, a tank of at least 20 gallons is recommended.

  • Care Level: Easy
  • Temperament: Peaceful
  • Tank Size: 20 gallons

10. Dwarf Gourami

A hardy and colorful species, Dwarf Gourami rank high as one of the top recommended beginner aquarium fish. Not only are they easy to keep and extremely adaptable, Dwarf Gourami also make excellent “centerpieces” for any aquarium due to their electric colors and large personalities.

Dwarf Gourami should be housed in aquarium at least 20 gallons in size. They are generally peaceful in nature, but can become territorial if placed in small tanks with other fish. Some suitable tank mates include Cory Catfish, Guppies, Platies, and Endlers.

  • Care Level: Easy
  • Temperament: Semi-Aggressive
  • Tank Size: 20 gallons

11. Goldfish


Goldfish are the most popular freshwater aquarium fish of all time (by far). Much to the surprise of most beginner aquarists, Goldfish come in tons of different varieties and colors (many of which are very easy to keep).

Much like Betta fish, the idea that Goldfish can live in bowls is completely wrong. In reality, Goldfish tanks should be at least 20-30 gallons.

Besides the slightly large minimum tank size, Goldfish are extremely easy to keep and do well in a wide range of conditions, making them the perfect beginner fish. That said, they prefer a cooler environment than most tropical aquarium fish (68-75°F), so they tend to do best in goldfish-only tanks. Goldfish also do well on a simple flake food diet, so no special feeding is required.

  • Care Level: Easy
  • Temperament: Peaceful
  • Tank Size: 20-30 gallons

12. Convict Cichlid

convict cichlid

In my opinion, Convicts are one of best beginner Cichlids out there for new aquarium owners. In fact, my first ever fish was a male Convict Cichlid (and I still own a few of his offspring nearly 20 years later!).

If you have any interest in breeding fish, Convict Cichlids are definitely the way to go. As long as your tank is stable and you have a male/female pair, not much else is required for these fish to spawn – and as a hardy species, Convict fry as pretty easy to raise.

Be warned, though – as a species of Cichlid, Convicts aren’t always the most friendly fish (especially when they are spawning or caring for fry). If you decide to go with Convict Cichlids, save yourself the headache and avoid adding any tank mates.

  • Care Level: Easy
  • Temperament: Aggressive
  • Tank Size: 20 gallons

13. African Cichlids

yellow lab african cichlid

The term “African Cichlid” is a blanket term that includes tons of different Cichlid species (over 1,200) – some of the most popular include the Yellow Lab Cichlid, Peacock Cichlid, and Zebra Cichlid.

In general, African Cichlids tend to be colorful, hardy, and prolific breeders. As with most cichlids, though, they can be a bit aggressive – choose tank mates carefully if you want to house them with other species.

Most African Cichlids are mouth-brooders, meaning they hold offspring in their mouths for 3-4 weeks until they can fend for themselves. If you have any interest in breeding fish and want something unique, I highly suggest looking into African Cichlids – the mouth-brooding process is truly amazing to watch.

  • Care Level: Easy
  • Temperament: Semi-Aggressive
  • Tank Size: 20 gallons

14. Red Cherry Shrimp

red cherry shrimp

Red Cherry Shrimp aren’t technically fish, but they’re interesting nonetheless. Small, colorful, and easy to keep, Red Cherries are the most popular freshwater aquarium shrimp out there.

While most shrimp are especially sensitive to water conditions, Red Cherries have been selectively bred for hardiness. That said, Red Cherry Shrimp still require good water conditions to thrive. In addition, Cherry Shrimp are best kept in shrimp-only tanks – otherwise, they usually become an unfortunate snack for hungry fish.

  • Care Level: Moderate
  • Temperament: Peaceful
  • Tank Size: 10 gallons

15. Cherry Barb

cherry barb

If you’re looking for a colorful aquarium fish, Cherry Barbs are hard to beat. These bright-red Barbs and not only eye catching and energetic, but also very easy to care for.

One great thing about Cherry Barbs is that they are just as content by themselves as they are in community tanks with other fish. Although they are generally peaceful and get along with other species, these Barbs can be a bit skittish when kept around more aggressive fish.

Overall, Cherry Barbs are a great beginner fish that add a sense of liveliness to any aquarium they reside in.

  • Care Level: Easy
  • Temperament: Peaceful
  • Tank Size: 20-30 gallons

16. Tiger Barb

tiger barb

The Tiger Barb is a lively, energetic fish famous for its recognizable orange and black striped pattern. As a schooling fish, Tiger Barbs should be kept in groups of 5-6 for best results.

In my opinion, Tiger Barbs are one of the most entertaining fish to watch – these little things NEVER stop moving. That said, they can be a bit nippy. Be careful when keeping them with long-finned fish such as Angelfish.

As an omnivorous species, Tiger Barbs should be fed a mix of flake food and meaty food (frozen brine shrimp or bloodworms) for optimal health. They also feel most “at home” in planted aquariums, but plants definitely aren’t an absolute must.

  • Care Level: Easy
  • Temperament: Peaceful (though slightly nippy)
  • Tank Size: 20-30 gallons

17. Oscar Cichlids

Oscar fish (Astronotus ocellatus)
  • Scientific Name: Astronotus ocellatus
  • Common Names: Oscar, Oscar fish, Marble Cichlid
  • Care Difficulty: Moderate
  • Temperament: Semi-Aggressive
  • Minimum Tank Size: 75 gallons

Oscar fish are a big commitment, with similar lifespans to dogs. They also have very similar personalities to dogs and are often called “water puppies”.

Oscars can learn to recognize their owner and normally respond very positively to them, with some going as far as allowing their owners to pet them.

If you are able to provide the appropriate space, food, and water changes your Oscar needs, then taking care of them will be a snap. Larger tanks are actually much better for beginners than smaller tanks.

A huge part of fish keeping is water chemistry, and water chemistry is more likely to change rapidly in a small tank than a large tank, so if something starts to go sideways, you will have much more time to fix it in a larger tank.

Oscars are also very hardy and forgiving fish, which makes them suitable for beginners. In addition, most other hardy fish are not nearly as beautiful as the Oscar, nor do they have as many color variants.

As long as a beginner has the space for one and knows they are signing up for 10+ years of care, the Oscar is a great pet, and they will stay loving and entertaining for their whole lives.

 18. Platies

platy fish
  • Scientific Name: Xiphophorus maculatus
  • Common Names: Platy, moonfish
  • Care Difficulty: Easy
  • Temperament: Peaceful
  • Minimum Tank Size: 10 gallons

One of the hardiest fish out there, the platy comes in a massive variety of styles and colors. Platies are a hardwater fish, so while they are extremely durable, you will have issues with keeping them in soft water.

They are also a live bearing fish, meaning they give birth to well-developed live young, instead of eggs like most other fish. Platies are some of the easiest fish to breed, and some of the best fish to get started with, both in terms of breeding and overall fish care.

The young do not need any special care, aside from their food being smaller than the adults’ food. They are born fully functional, though you may want to provide extra hiding areas, as the adults can be cannibalistic.

One way or another, if you have a female, she will give birth, and some of the young will survive. Be sure you have enough space to house them or have other homes lined up for them.

Platies are a great interactive fish, easy to care for, and can adapt to very hard water that other fish cannot. Despite their cannibalistic nature, platies are very calm and peaceful fish, and can be kept with a wide range of tankmates.

19. Pearl Gourami

pearl gourami
  • Scientific Name: Trichopodus leerii
  • Common Names: Lace Gourami, Mosaic Gourami
  • Care Difficulty: Easy
  • Temperament: Peaceful
  • Minimum Tank Size: 20 gallons

The pearl gourami, aptly named for the beautiful, white, circular patterning across their bodies, is a gorgeous and easy to care for fish. They are one of the most exotic looking fish on this list and are often used as centerpiece fish in aquariums.

Pearl gourami do wonderfully in community aquariums, as long as there are not other labyrinth fish. Gourami, which are labyrinth fish, can play well with other types of fish, but often do not play well with one another.

A labyrinth fish has both gills and a labyrinth organ, which is essentially a primitive lung. Ensure your gourami can access the top of the water to breathe air whenever they want, or else they may begin to suffocate.

Pearl gourami are easy to feed, not overly picky with water hardness (though they prefer soft water), and do not require more maintenance than other fish.

They have a wonderful and unique look, and will look great in just about any aquarium you put them in. Pearl gourami are very intelligent and interactive and make wonderful pet fish.

20. Discus

  • Scientific Name: Symphysodon. discus, tarzoo, aequifasciatus, haraldi
  • Common Names: Discus, Pompadour Fish, King of the Aquarium
  • Care Difficulty: Intermediate
  • Temperament: Peaceful
  • Minimum Tank Size: 60 gallons

The Discus fish, commonly held as a holy grail in fish keeping and regarded as one of the most difficult to care for fish, can actually be kept by beginner fish keepers. While it is not recommended to keep Discus as your very first fish, it can be done.

When you first start keeping Discus, you will want to start with some of the lower-grade fish, though these will still cost $20-40 USD each. Discus are more demanding than your average fish, so it helps to have experience with at least one other fish before moving to Discus.

Recently, there have been several lower-grade strains that could easily be regarded as hardy, meaning the average fish keeper can successfully house these fish.

Their main issue is nitrates; while most fish tolerate 20-40ppm just fine, it is best to keep the nitrates in a Discus tank between 0-10ppm. Essentially, these fish need more water changes than other fish, primarily due to their meat heavy diet, which produces a lot of nitrogenous waste.

As long as you can provide a large tank, appropriate food (which often includes beef heart and homemade meals), a school of Discus (at least 6), enough filtration, and a solid time commitment, you should have no trouble keeping them. And wouldn’t it be wonderful to successfully start you fish keeping journey by keeping the most beautiful freshwater fish in the hobby?

21. Killifish

Killifish in freshwater aquarium
  • Scientific Name: Fundulus
  • Common Names: killifish, killie, topminnow
  • Care Difficulty: Beginner, Intermediate, Advanced, depending on the species
  • Temperament: Peaceful
  • Minimum Tank Size: 10-20 gallons

While there are hundreds of species of killifish, here we will go over some of the common aspects of care. Most species you can find for sale will fall under this category and general care, as the sensitive ones are normally only sold online.

Most species are incredibly hardy, and while they are prone to jumping, they do not have any other downsides. They can have absolutely magnificent coloration, such as f. gardneri, though there are hundreds of bold colored killifish.

Unlike the other fish on this list, killifish do best in a species only tank, or a tank that only houses one species of fish. They can be skittish and tricky to feed, so a community tank can cause a lot of stress for them.

Simply because there are so many species, and because each one has slightly different requirements, they do require more in-depth research than other beginner species.

Despite this, their hardiness and cute little personalities do make for perfect beginner fish.

22. Rainbowfish

Boeseman's rainbowfish
  • Scientific Name: Melanotaeniidae
  • Common Names: Rainbowfish
  • Care Difficulty: Beginner to Intermediate
  • Temperament: Peaceful
  • Minimum Tank Size: 55 gallons

Rainbowfish are large and brilliantly colored schooling fish, normally best suited for equally large community tanks.

They are incredibly active, which can make other fish feel safer, and are very hardy and easy to take care of. Rainbowfish are not at all picky, nor aggressive.

A few species can be difficult for a beginner to care of, though these are not commonly found in stores, so there is little chance that a beginner accidentally buys a difficult rainbow fish.

They do best in heavily planted tanks, as they like to weave in and out of the plants. In addition, green plants provide a beautiful contrast to their bright colors and can really make them pop.

23. Angelfish

angelfish species
  • Scientific Name: Pterophyllum scalare
  • Common Names: Angelfish, Freshwater Angelfish
  • Care Difficulty: Beginner
  • Temperament: Semi-Aggressive
  • Minimum Tank Size: 29 gallons

The freshwater angelfish is an often-overlooked fish, for absolutely no good reason. Many people are surprised to find that these wonderful animals do not just exist in saltwater and are even more surprised to find the variety of freshwater angelfish.

Freshwater angelfish have been domesticated for a relatively long period of time and there is a multitude of breeds available. You can get a massive variety of colors, fin shapes and sizes, and even scale types; they’re essentially just as versatile as betta fish!

Another aspect that is similar to betta fish is their aggression; angel fish are cichlids, and most cichlids have distinct personalities and temperaments. While one angelfish may be perfectly passive towards its tank mates, another will be mildly to severely aggressive towards.

You do not need to be experienced to deal with an angelfish’s aggression, as it is not normally severe, and can often be easily managed. As long as you research ways to handle the potential aggression before it happens, you will be good to go.

Cichlids, despite their potentially aggressive nature, are normally great starter fish. They are hardy, strong, very personable, and are a great pet to own. They have distinct and unique personalities that cannot be replaced, and it is impossible not to get attached to them.

24. Firemouth Cichlids

firemouth cichlid
  • Scientific Name: Thorichthys meeki
  • Common Names: Firemouth, Fire Cichlid
  • Care Difficulty: Beginner to Intermediate
  • Temperament: Semi-Aggressive
  • Minimum Tank Size: 29 gallons

Firemouth cichlids are stunning and hardy fish, perfect for beginners. They are flashy, iridescent, and can light up any tank.

They also thrive in a wide range of water parameters, so nothing needs to be done to provide them with special water or alter the water you already have.

Like other cichlids, they can be aggressive, especially when breeding, but as long as you chose tank mates of a similar size, the aggression will not last long.

Provide plenty of decorations such as rocks and driftwood, as these double as sight breaks and potential territories. If your cichlid can establish a territory around one or two decorations that they feel safe in, the tank will be peaceful.

25. Pictus Catfish

pictus catfish
  • Scientific Name: Pimelodus pictus
  • Common Names: Pictus catfish, Pictus cat
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 55 gallons

The pictus catfish is one of the most classic looking aquarium catfish that a beginner can own. They have light gray bodies with bold black spots, and massive barbells, or whiskers, which give them that “catfish” look.

Other catfish in aquariums, such as pleco catfish, do not have large whiskers, and may not be immediately recognized as catfish.

Pictus catfish will shoal if you keep them together, but you will need a much larger tank. They are peaceful inhabitants of community aquariums, as long as there are enough decorations for them to hide in and among.

These catfish are very active and do not stay at the bottom of the aquarium. Expect to see them swimming around in the mid-section frequently, and plan tank mates accordingly.

While they are peaceful, they will eat smaller tank mates when hungry, so it is best to house them with larger fish.

26. Clown Loach

Chromobotia macracanthus - clown loach
  • Scientific Name: Chromobotia macracanthus
  • Common Names: Clown loach, tiger botia, tiger loach
  • Care Difficulty: Beginner to Intermediate
  • Temperament: Peaceful
  • Minimum Tank Size: 125 gallons

Clown loaches have large, bold, vertical black and yellow stripes, which make them stand out in any aquarium. They are boisterous and have to be kept in groups, so there is no way for them to blend into the background.

Many people get them in order to deal with snail infestations, but you need to be sure that you will be able to house a group of these large fish. They simply will not survive in small tanks, but the bigger the tank you put them in, the happier and more active they will become.

Clown loaches do require quite a few hiding areas in order to be safe and stress free, thus reducing the chances of them getting sick.

They are active during the day, unlike most loaches, so feeding them in a community setting will not be an issue. As long as you can manage their size, you will not have any difficulties in taking care of this fish, and their personalities make it impossible for you to regret keeping them.

27. Harlequin Rasboras

harlequin rasbora
  • Scientific Name: Trigonostigma heteromorpha
  • Common Names: Harlequin rasbora, porkchop rasbora
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 20 gallons

Harlequin rasboras are a wonderful, hardy schooling fish. They fit well into community aquariums and are very adaptable in terms of water hardness.

Harlequin rasboras are also quite beautiful, presenting red bodies with a large, pork chop like black marking and shimmering iridescence.

Very few fish keepers ever encounter issue with this fish, and they truly are one of the easiest fish to keep and care for. They are not skittish and will not present any behavioral issues as long as their school is large enough.

Harlequin rasboras can also be much more interactive than the average schooling fish, and all of these combined factors make them perfect beginner fish.

28. Marble Hatchetfish

Marbled hatchetfish (Carnegiella strigata)
  • Scientific Name: Carnegiella strigata
  • Common Names: Marbled Hatchetfish
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 10 gallons

There isn’t anything quite like a hatchetfish, and the marbled hatchetfish is no exception. They have a gorgeous opalescent white and black marbled pattern, and the unusual body shape of a hatchet. They spend their time swimming just under the surface of the water, darting around in small groups.

When housed with other small fish, they make wonderful community inhabitants, and their activity often encourages other fish to come out of hiding.

As long as you keep nitrates low, and the water isn’t very hard, you will have no issues with this fish. However, keep in mind that they can be prone to jumping, so be sure to completely cover your tank.

29. Upside-Down Catfish

  • Scientific Name: Synodontis nigriventris
  • Common Names: Upside-down catfish, Blotched catfish
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 10 gallons

While an upside-down fish is normally a very bad sign, this little fish almost exclusively swims in an upside-down position. They normally rest upside down in decorations as well, and live most of their lives in this position.

They have very large eyes and barbels, and very unique shaped fins. Upside down catfish present an almost desert like pattern, with various shades of tan and brown patches, similar to a lizard. They do best in small schools and are great peaceful inhabitants of community tanks.

30. Celestial Pearl Danios

Danio margaritatus - celestial pearl danio
  • Scientific Name: Danio margaritatus
  • Common Names: Celestial pearl danio, cpd, galaxy rasbora
  • Care Difficulty: Easy
  • Temperament: Peaceful
  • Minimum Tank Size: 10 gallons

Celestial pearl danios, also known as galaxy rasboras, are a very small schooling fish. If they are housed with tankmates of a similar size and temperament, they will do wonderfully in a community tank.

They prefer planted tanks, as they can be quite skittish, and plants provide perfect natural hiding areas, as well as making their coloration stand out.

CPD’s have medium gray bodies with white spots and bold, contrasting orange and red fins. Just like other schooling fish, they need schools of at least 6 in order to feel comfortable.

Feeding and overall maintenance is not an arduous task for these little guys, and they are not overly demanding in their care.

31. White Cloud Minnows

Tanichthys albonubes
  • Scientific Name: Tanichthys albonubes
  • Common Names: White cloud mountain minnow, White cloud minnow, WCMM
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 10 gallons

White cloud mountain minnows (WCMM) are adorable and flashy little fish. While they were only recently introduced into the hobby, they have become quite popular in a short period of time.

Their lively and peaceful nature, coupled with their white bodies and colorful red fins, make them perfect for many aquariums.

In terms of hardiness, this fish may very well be the hardiest fish on this list. They are durable in terms of adaptability to various water parameters, their food, school size (though it needs to be at least six), tank mates, and they can thrive in water from 45 to 85 degrees Fahrenheit. This fish is not at all demanding and is great for learning the ropes of fish keeping.

32. Bichir

bichir fish in aquarium
  • Scientific Name: Polypteridae
  • Common Names: Bichir, Dragonfish
  • Care Difficulty: Intermediate
  • Temperament: Peaceful
  • Minimum Tank Size: 50-125 gallons

While bichirs are generally regarded as a difficult fish to keep, anyone who has done proper research and can properly feed them will be able to let this fish thrive.

Bichirs aren’t necessarily aggressive, but they will attempt to eat any smaller fish in the tank. While other fish prefer community tanks, as the activity of other species make them feel safer, bichirs have no preference toward either a community tank or a species only tank.

In terms of feeding, they have voracious appetites, so the issue is not getting them to eat, rather, their food can be quite expensive. They require frozen food, such as shrimp, mussels, clams, worms, and fish to be a primary part of their diet, and the cost for these can add up quickly.

Despite this, owners rarely find the cost an issue, simply because bichirs are so incredibly unique and fun to keep. There are no other fish quite like them, and nothing else exhibits the same personality.

33. Gold Barb

golden barbs
  • Scientific Name: Puntius semifasciolatus
  • Common Names: Gold barb, Chinese Barb
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 20 gallons

The gold barb is a large and flashy schooling fish, presenting a gold body with black speckling and bright red fins. Planted aquariums are especially good at drawing out the color of these fish, which will attract a lot of attention to your tank.

Schooling fish can get nippy if their school is too small, and the gold barb is no exception. They aren’t particularly aggressive, but if they are uncomfortable in their school, they may lash out at other species in the tank. Luckily, this is easily resolved with the addition of a few more gold barbs.

It is impossible to be disappointed with these gorgeous fish and flashy colors, especially because they do so well in community tanks.

While they are not often centerpiece fish, they are great for enhancing other colors in the tank and helping with the overall aesthetic. Gold barbs are good beginner fish due to their hardy nature, calm demeanor, and ability to peacefully interact with other fish.

34. Rosy Barb

rosy barb
  • Scientific Name: Puntius conchonius
  • Common Names: Rosy barb
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 29 gallons

While they get larger than gold barbs, and most barbs for that matter, rosy barbs are not aggressive or overly boisterous. Their size makes them more compatible with larger fish than other barbs, but otherwise has little impact on their care.

Rosy barbs are aptly named for their stark red coloration and highly iridescent scales, which reflect a soft pink color. Other coloration is sparse and varies from fish to fish, but they normally have a black dot at the beginning of their tail and black on the tips of their fins.

Keeping a properly sized group of at least six is very important for rosy barbs, as they do have a tendency to bite the fins of other fish if their school is too small.

Aside from this, they are an absolute joy to own, and will brighten any tank. They are extremely hardy, not picky eaters, and work very well in community tanks and with other peaceful fish.

Most are also able to handle semi-aggressive fish very well, so options for tankmates are not as limited as they are with other barbs.

35. German Blue Ram

german blue ram
  • Scientific Name: Mikrogeophagus ramirezi
  • Common Names: German Blue Ram, Butterfly Cichlid, Ram Cichlid
  • Care Difficulty: Moderate
  • Temperament: Semi-Aggressive
  • Minimum Tank Size: 20 gallons

The German blue ram may be the most beautiful beginner cichlid. These fish are well suited for smaller tanks and do very well in pairs and small groups, though they should also have other tank inhabitants to act as dither fish.

Some can be picky with their food but feeding them frozen treats 1-2x a week is normally enough to turn them in the right direction.

They will make some minor readjustments to the tank layout, so expect to see some stones and gravel moved around every now and again.

Even though they are very small, they have huge personalities and aren’t afraid to show off to the other fish. Watching them interacting with one another and their tank mates is both intriguing and hilarious, depending on their mood. I have never met anyone who regretted owning this little fish, even a few beginners!

36. Cockatoo Cichlid

cockatoo cichlid
  • Scientific Name: Apistogramma cacatuoides
  • Common Names: Cockatoo Cichlid, Big Mouth Cichlid
  • Care Difficulty: Beginner
  • Temperament: Semi-Aggressive
  • Minimum Tank Size: 29 gallons

The cockatoo cichlid, also known by its scientific name Apistogramma cacatuoides, is a bold colored, thin bodied little fish. They are intelligent and personable, make wonderful pet fish, and are often used as centerpiece fish in community aquariums due to their brilliant markings.

While their bodies are tan/gray with one horizontal black stripe, their fins are black, splashed with orange, red and yellow in a bold, flame-like pattern. They are eye catching, hence their position as centerpiece fish, but also non-aggressive, and get along with other fish well, except during breeding.

Cockatoo cichlids need a well decorated tank with several small caves and hides. They prefer tight fitting caves, and caves that only have one entrance/exit.

These cichlids are not very demanding in any other aspect and work wonderfully in species only and community settings.

37. Jack Dempsey

Jack Dempsey cichlid
  • Scientific Name: Rocio octofasciata
  • Common Names: Jack Dempsey, Electric Blue Jack Dempsey
  • Care Difficulty: Intermediate
  • Temperament: Aggressive
  • Minimum Tank Size: 60 gallons

The Jack Dempsey Cichlid is probably the second most aggressive fish on this list, and despite this fact, they can still be successfully kept by a beginner. They are strikingly beautiful, as their dark bodies are speckled with bright colored iridescent and opalescent scales, changing with every movement they make.

Understand that aggressive fish require more care and maintenance than peaceful fish, so a Jack Dempsey will require much more care than the other fish on this list.

They also need larger tanks, more expensive food, and more expensive filtration. These are obstacles for beginners, but by no means do they prevent a knowledgeable beginner from properly caring for this fish.

All cichlids have individual personalities, but the larger they get, the more personable they tend to become. Everyone who owns a Jack Dempsey absolutely loves their fish; it’s like having a smaller, water-bound version of a dog.

38. Green Texas Cichlid

green texas cichlid
  • Scientific Name: Herichthys cyanoguttatus
  • Common Names: Green Texas Cichlid, Texas Cichlid
  • Care Difficulty: Intermediate
  • Temperament: Aggressive
  • Minimum Tank Size: 60 gallons

The Green Texas Cichlid is the most aggressive fish on out list; the same rules about aggression listed for the Jack Dempsey apply. Both fish should only be housed with fish of a similar temperament and size, so the tank is successful. However, if your Texas cichlid decides that it’s breeding season, it will attempt to kill any fish it sees.

They are also highly territorial, so it is important to provide several large decorations. It will claim one or several of these as its territory and will spend most of its time around these decorations. As long as other fish in the tank don’t mess with its territory, everything will be peachy.

Feeding time may cause some minor aggression, but it doesn’t often last long, nor does it cause significant damage to any of the fish.

If you are intrigued by interpersonal relationships between various fish, then an aggressive tank is the tank for you.

Keeping large fish with boisterous personalities is a great way to observe these relationships and interactions, and it allows you to personally manage them to prevent damage.

39. Odessa Barb

Odessa Barb
Anandarajkumar at English Wikipedia [CC BY-SA 3.0]
  • Scientific Name: Pethia padamya
  • Common Names: Odessa Barb, Scarlet Barb
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 20 gallons

Odessa barbs are silver bodied fish with a bold, horizontal red stripe from their head to their tail. Their scales appear perfectly outlined in black, with some black appearing on the fins, and their highly iridescent scales make some scales appear white.

A school of these fish look fantastic in any tank, and there are not any similar barbs or tetras that can take their place. Odessa barbs are peaceful and hardy, and while they do best and look best in planted tanks, this is not necessary for their overall wellbeing.

They rarely have issues with their tank mates, unless they are housed with a highly aggressive fish, and they remain peaceful even during the breeding season. Odessa barbs are hardy and will survive many newbie mistakes that other fish may not.

40. Asian Stone Catfish

  • Scientific Name: Hara jerdoni
  • Common Names: Asian Stone Catfish, Stone Cat
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 10 gallons

This tiny little fish won’t do much to spice up the visual aesthetic of your tank, but their unique size and behavior makes them a must have, at least once in your fish keeping career. It is best to keep an adorable little group of these fellows in the same tank.

They have a small, almost banjo like body shape, long barbels, and large triangle shaped fins.

Asian stone catfish can thrive in very small tanks, as they are not that active, but it is best for a beginner to get a tank larger than their minimum tank size.

A smaller tank is prone to rapid changes in water chemistry, which can be difficult or impossible to fix. Larger tanks allow more mistakes and variability, which is ideal for beginners.

While Asian stone catfish are not picky eaters, it can be difficult for them to get enough food in a community aquarium.

Do not add any other bottom feeding fish, or else these little ones run the risk of starvation. As long as they are the only bottom dwelling species, they will thrive in a community or species only aquarium.

41. Diamond Tetra

Moenkhausia pittieri
  • Scientific Name: Moenkhausia pittieri
  • Common Names: Diamond Tetra
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 29 gallons

Diamond tetras have pure silver, slightly raised, and highly iridescent scales, which gave them their “diamond” name. They have some slight red coloration around the top of their eyes, but aside from this, their bodies resemble gemstones.

This fish thrives in softer water, though they can tolerate moderately hard water. As long as your water parameters fall somewhere in that range, then congratulations – you can easily keep these fish!

These tetras are non-aggressive schooling fish and can peacefully interact with most other fish. They are not difficult to feed, nor do they hog food and prevent other fish from eating. Aside from water hardness, they do not require any specialized care and are quite hardy.

42. Cardinal Tetra

cardinal tetra
  • Scientific Name: Paracheirodon axelrodi
  • Common Names: Cardinal Tetra, Red Neon
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 20 gallons

Cardinal tetras are an alternative to neon tetras. In some areas, neon tetras are becoming much weaker – whether this be poor genetics or improper care, they are not nearly as healthy as they once were.

Cardinal tetras are newer to the fish keeping scene than neon tetras, but they look very similar. Cardinals have a silver body with a thick horizontal blue stripe through the middle of their body, and a thick red stripe taking up the bottom half of their bodies.

The shades of blue and red are nearly identical to those of a neon tetra, and the primary differences between the two are that Cardinals get larger than neons and have less silver on their bodies.

These tetras require schools of at least six and should only be housed with other peaceful tank mates.

They are popularly used in community planted tanks, as their blue and red stands out against green plants, and those hues are difficult to find in other schooling fish.

43. Blood Parrot Cichlid

blood parrot cichlid
  • Scientific Name: Amphilophus citrinellus x Paraneetroplus synspilus
  • Common Names: Blood Parrot Cichlid, BP, Bloody Parrot
  • Care Difficulty: Intermediate
  • Temperament: Peaceful
  • Minimum Tank Size: 55 gallons

This perpetually smiling fish often look quite adorable, though they can actually be aggressive. However, they are an artificially created species, and even if they want to act aggressively towards another fish, their deformed mouths prevent them from doing so.

Their entire bodies are a medium pink to red color and are misshapen when compared to other fish. They tend to be very round, with a distinct separation between the head and the body.

While the appearance of this fish, including their permanently cute faces, can freak some people out, it is aesthetically appealing to other people.

Since they are unable to act aggressively towards other fish, they do very well in community settings.

Blood parrots need plenty of hiding areas to feel secure and establish a territory. They also like to dig around in the substrate and rearrange some decorations, so be sure that there is nothing too sharp or rough in the tank.

Blood parrots have adorable personalities to match their adorable faces and are fascinating to watch.

44. Rainbow Shark

rainbow shark in aquarium
  • Scientific Name: Epalzeorhynchos frenatum
  • Common Names: Rainbow shark, Red Fin Shark
  • Care Difficulty: Beginner
  • Temperament: Semi-Aggressive
  • Minimum Tank Size: 55 gallons

Rainbow sharks can be found in nearly every pet store, though not everyone is equipped to keep this fish. They can get quite large, which is attractive to some fish keepers, while others love their colors and personalities.

Decorations are a must for this fish, as they are semi-aggressive and territorial, and they need decorations to build their territory around.

Without any decorations, they will claim the entire tank as their territory, which will cause severe aggression issues with any other fish.

They are normally kept in community tanks, which works out very well, as long as they establish a suitably sized territory. Species only tank with rainbow sharks are rare, as they cannot be housed with one another.

Even though Rainbow sharks are incredibly active and interesting to watch, a 50-60-gallon tank with a single fish isn’t as interesting as a 50-60-gallon tank with one large, interesting fish, and 4 smaller schools of fish.

These fish have always been a popular choice, due to their hardy nature, active personalities, and beautiful coloration. This won’t be changing anytime soon.

45. White Skirt Tetra

Gymnocorymbus ternetzi
  • Scientific Name: Gymnocorymbus ternetzi
  • Common Names: White Skirt tetra, skirt tetra, gold skirt tetra
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size:  20 gallons

White skirt tetras are an easy to care for fish and are very undemanding in their overall care. They are not at all picky when it comes to food or decorations, though they require both.

Since they are a schooling species, they need a group of at least 6 to feel secure.

White skirt tetras are a partially translucent, flesh colored fish, though there are several other color variants. Avoid those with unnatural colors, especially blue and bright pink, as these are normally dyed fish. They will either lose their color or live shorter life spans.

The only exception are the glo-fish versions of white skirt tetras, which live normal lives and have no side effects from their unnatural, yet appealing, coloration.

46. Bloodfin Tetra

Aphyocharax anisitsi bloodfin tetra
  • Scientific Name: Aphyocharax anisitsi
  • Common Names: Bloodfin tetra
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 20 gallons

Bloodfin tetras are aptly named, because while their bodies are a plain silver, their fins are a stark red.

Despite their bloody sounding name, they are perfectly peaceful and must be kept with others of their own kind. Their unique coloring has an impressive appearance when they school, and many aquarists utilize this to perfect their community tanks.

This hardy fish will present very few care requirements and can thrive in most water, though softer water is preferred.

As long as you give them food and regular water changes, they will spend their time blissfully darting around the aquarium.

47. Redeye Tetra

Redeye tetra (Moenkhausia sanctaefilomenae)
  • Scientific Name: Moenkhausia sanctaefilomenae
  • Common Names: Redeye tetra, lampeye tetra
  • Care Difficulty: Beginner
  • Temperament: Peaceful
  • Minimum Tank Size: 20 gallons

Redeye tetras are a silver bodied fish with a red ring around their eyes with two vertical bands on their tail, one white and one red. Although this sounds like a plain looking fish, once in a school, their red eyes stand out in a unique way that other fish cannot replicate.

Housing them with other peaceful tankmates is a must, as they are unable to defend themselves against aggressive tankmates. In addition, they prefer to have several decorations large enough to dart in and around, as this will help them feel even more secure and safe.

Similar to the other schooling fish on this list, redeye tetras are most commonly found in community tank settings, especially beginner community tanks.

They are hardy, undemanding, and peaceful, which means that there is a very low possibility of running into any issues.

48. Raphael Catfish

  • Scientific Name: Platydoras armatulus
  • Common Names: Raphael Catfish, Striped Raphael Catfish
  • Care Difficulty: Intermediate
  • Temperament: Peaceful
  • Minimum Tank Size: 29 gallons

The Raphael Catfish has alternating black and cream horizontal stripes across its body, coupled with very long barbels and fins. This catfish is somewhat odd-looking, especially when its tadpole shaped body is taken into consideration.

They cannot be netted like normal fish, as their long fins and hidden spines can easily get stuck in the net, trapping the fish, with no safe way to get them out.

Aside from the inability to use a net, their care is pretty straightforward. They are not particularly picky eaters, though they do require a mix of high-quality pellet and frozen food.

Raphael catfish are also not particularly active, and spend much of their time hiding in decorations, plants, and driftwood.

Due to this, they are commonly kept in community tanks, especially those with larger fish. Large fish do not often bother with slow moving nocturnal fish, and the Raphael catfish is no small fry.

They also do well in community tanks with more peaceful fish. Either way, be sure to drop extra food in the tank about an hour after the lights go off, as this gives the catfish a chance to eat without another fish snatching up their food.

49. Glass Catfish

glass catfish - Kryptopterus vitreolus
  • Scientific Name: Kryptopterus vitreolus
  • Common Names: Glass catfish, glass cat, phantom catfish
  • Care Difficulty: Intermediate
  • Temperament: Peaceful
  • Minimum Tank Size: 29 gallons

The glass catfish is an incredibly unique fish, lacking scales, a dorsal fin, and all body pigmentation. They are as see-through as jellyfish, aside from their bones. While this can freak some people out, most find it incredibly fascinating.

Glass catfish require schools of 6 or more and do best in heavily planted and heavily decorated aquariums. They have a skittish nature, and without a proper amount of hiding areas, they will be constantly stressed, especially in a community tank.

These catfish are more sensitive to fluctuations in water parameters, primarily hardness and pH, so be sure to acclimate this fish to their new home slower than you would with other fish.

In addition, large water changes over 50% may cause undue stress, so it is best to change around 30% weekly, depending on your nitrate level.

They are not picky eaters, nor do they have any other complex requirements, so a dedicated beginner would be able to successfully keep this unique species.

50. Otocinclus

Otocinclus catfish in planted aquarium
  • Scientific Name: Otocinclus
  • Common Names: Otocinclus, Oto, Dwarf Sucker
  • Care Difficulty: Intermediate
  • Temperament: Peaceful
  • Minimum Tank Size: 20 gallons

The Otocinclus catfish, or “Oto” for short, is a tiny catfish that has cream, brown, and black coloration, though the patterning depends on the species. These little fellows need to be kept in moderately large schools and a fully established tank.

The difference between a cycled tank and an established tank is essential in keeping this fish. While a cycled tank can convert ammonia to nitrate rapidly, which avoids poisoning and killing your fish, an established tank is cycled and has high levels of biofilm and non-harmful algae. Cycling normally takes around a month, while it normally takes three months to achieve an established tank.

Otos have a symbiotic relationship with bacteria in their gut; they primarily feed on plant matter and algae but are unable to digest this. The bacteria will digest it for them, and both species are benefited.

However, if otos are placed in a tank with little to no biofilm and algae, the bacteria in their gut will die off, and the fish will starve.

If your otos are captive bred, they are much more likely to accept blanched vegetables and algae wafers. However, the majority are wild caught fish, and will take several days to several weeks to adjust to their new food, hence the need for an established tank.

Aside from this particular issue, otos are a fun and active little fish to keep and are so peaceful that they are the only fish that can be housed with baby dwarf shrimp.

As long as their tank is cycled and has stable parameters, anyone can care for this fish. They can also thrive in a community setting, and you will see them darting around the whole tank, going from decoration to decoration.

How to Start a Freshwater Fish Aquarium

fish tank

Setting up your fish tank correctly the first time can save you a ton of time and money in the long run. Here is our step-by-step beginners guide for how to start a freshwater fish aquarium:

Step 1: Gathering the Equipment

Picking out the right equipment is vital to the success of your tank. Remember, fish should not be kept in bowls. If you’re interested in buying a complete kit, we recommend the Marina 20 Gallon Kit. It contains most of what you need to get a tank running and is much better than other kits on the market.

Marina Aquarium Kit - 20 gallon Fish Tank - LED
  • 20 U.S. gallon glass aquarium
  • Includes a Marina Slim S20 clip on filter with...
  • Includes everything you need to get your aquatic...

If you’re looking for a more custom setup, here are a few things you will need:

  • Tank: A lot of beginners make the mistake of thinking small tanks are easier. In reality, the tiny water volume of small tanks makes it very hard to control water parameters. In my opinion, 20 gallons is the magic number for first time fish keepers – large enough to offer some stability, but small enough so it’s not a ton of work.
  • Filtration: Unless you’re keeping really difficult fish (which none of the above are), a hang-on-back filter should be more than sufficient. I’ve used the AquaClear Power Filter for years – it’s powerful and pretty quiet compared to other filters on the market.
  • Heater: A heater not only gives you precise control over the water temperature of your tank, but also allows you to create a stable environment for your fish. I recommend the Cobalt Aquatics NeoTherm.
  • Substrate: Most species on our list are fine with a simple gravel substrate (the only exception is Cory Catfish, which requires a softer sand substrate).
  • Water Conditioner: Water straight from the tap is not suitable for aquariums, as it contains chlorine and other harsh chemicals. Water condition removes these toxins and makes your tap water safe for fish.

Step 2: Setting up the Tank

Now that you have all the right equipment, it’s time to put everything together! Here are a few basic steps to follow when setting everything up:

  1. Rinse & Lay the Gravel: I can’t stress that first part enough – do not forget to rinse your gravel. Gravel straight from the bag will create a cloudy mess that is very hard to fix. Rinse until the water runs clean, then lay gently in the bottom of your tank.
  2. Fill & De-Chlorinate: Once the gravel is laid, it’s time to fill your tank! Pour water into your tank as gently as possible. Once filled, add the appropriate amount of water conditioner per the bottle’s instructions.
  3. Aquascaping: Now that the tank is filled with de-chlorinated water, feel free to let your creative process flow. Add decorations, live/fake plants, air stones, or anything else you desire.
  4. Heaters, filtration, lighting: Add your new heater, filter, and any other equipment you purchased.

Step 3: Cycling Your Aquarium

Cycling is the most important (although also the most ignored) step in setting up an aquarium. But what exactly is the cycling process?

In simple terms, the Nitrogen Cycle is the process of building up colonies of beneficial bacteria that convert harmful compounds (ammonia caused by fish waste and uneaten food) into safer compounds, such as nitrate.

Without these beneficial bacteria, Ammonia and Nitrite levels in your aquarium will skyrocket – which means serious problems for any tank inhabitants.

For the sake of making this article as short as possible, we’re not going to go through the entire process of completing the nitrogen cycle in this post. Instead, check out our beginner’s step by step guide to the nitrogen cycle here.

Step 4: Freshwater Aquarium Maintenance

Once your tank is cycled and your fish are swimming happily, all the hard work is done, right? Unfortunately, no…

In order to keep your tank healthy, regular maintenance is required. Here are a few things you should do to keep your aquarium running smoothly:

  • Weekly or bi-weekly water changes: Water changes are a great way to remove unwanted toxins (ammonia, nitrite, and nitrate) and re-introduce important trace elements that make for healthy fish. Make sure you always use water conditioner on the new water that you’re putting into your tank.
  • Regular testing: Testing your water chemistry regularly is the only way you can really understand what’s going on beneath the surface. The API Freshwater Master Test Kit is the best water tester on the market.
  • Filter cleanings: A lot of gunk tends to build up in the filter (obviously). That said, never wash your filter under sink water. Huge colonies of beneficial bacteria (which are vital to the health of your tank) that live in the filtration media will be wiped out by untreated water. Simply rinse your filter sponge in a small cup of tank water for best results.

Step 5: Monitoring Aquarium Water Chemistry

Now that your aquarium is up and running you will need to keep a continual eye on the water quality. If the chemistry shifts too far in a particular direction you can end up with sick or dead fish.

What’s more, what is healthy for one kind of fish might be toxic to another, especially where pH, water hardness, and salinity are concerned. So let’s take a closer look at how to monitor water quality for freshwater aquarium fish.

How to Lower Nitrates in Freshwater Aquarium

Once an aquarium is fully biologically cycled (see above), ammonia and nitrites should stop accumulating. However nitrate is the end result of the cycling process. While aquarium fish do tolerate moderate levels of nitrate eventually this compound can become toxic to fish.

Exactly what nitrate concentration is deadly depends mostly on the fish in question. Betta fish and goldfish are very tolerant of nitrates and won’t show ill effects unless the concentrations are greater than 30 parts per million (ppm). Meanwhile discus and many saltwater fish are quite sensitive to levels as low as 10 ppm.

The main way that nitrate leaves the system is through water changes. Old aquarium water is removed and fresh water added in. Live aquarium plants are another way since they use nitrate (as well as ammonia and nitrite) as fertilizer for their growth.

Ideally, you’d be doing both. While nitrates aren’t as poisonous as the other nitrogenous waste compounds they still don’t do fish any good. They also contribute to algae growth so we want to keep nitrates as low in concentration as possible.

How to Lower pH in Freshwater Aquarium

Another major parameter to track when caring for your freshwater aquarium is the pH. pH is a measure of the hydrogen ion concentration in a solution; i.e. how “acidic” or “alkaline” it is.

So what pH should a freshwater aquarium be? That actually depends on what kind of fish you have. Normally, tap water in developed countries is very hard (high GH/KH) and alkaline (high pH). For fish like livebearers and African cichlids these conditions are just right for them.

But what about fish that prefer a low pH like angelfish or tetras? These fish will sometimes survive in alkaline water but their appetites, colors, disease resistance, and willingness to breed are all affected. In the case of these low pH lovers we want conditions below a pH of 7.0 (neutral). Many of these fish even come from blackwater environments where the pH can be as low as 4.5.

The best way to lower the pH is to start off with water that is close to neutral. Then you can use small amounts of additives to bring down the pH. This means using reverse osmosis or distilled water for water changes.

How to Lower GH in Freshwater Aquarium

Using mineral-free R.O. and distilled water also has the added benefit of ensuring that minerals can’t build up in the water since acid-loving fish often prefer soft water as well. Hardness can be described and measured using both the GH (general hardness) and KH (carbonate hardness) scales.

Lowering general hardness means reducing the levels of calcium and magnesium in your aquarium water. And the two best methods of doing so both involve prevention, i.e. keeping minerals from getting in, in the first place.

Water softening pillows are capable of absorbing calcium and magnesium and are widely available. Though they have the downside of replacing these ions with sodium, increasing the overall salt content of your water.

Preventing evaporation – and topping off our aquarium with mineral-free water when it does happen – also keeps mineral levels low. Remember that tap water and minerals containing rocks or gravel are the main sources of GH. And the only way to avoid calcium and magnesium is to not add it via tap water or minerals.

How to Raise KH in Freshwater Aquarium

Sometimes we actually want a bit of mineralization, especially in the case of KH (carbonate hardness). kH is a measure of how stable your pH will be because carbonate acts as a buffer to swings brought about by acidifying agents like plant tannins or carbon dioxide.

So how to raise alkalinity in freshwater aquariums? The easiest way is to add a bit of carbonate in the form of baking soda. One teaspoon per 13 gallons will raise the KH by 4 degrees.

However in most aquariums you will naturally have both a high GK and high KH. This is because both minerals are found together naturally in rocks and other sources of minerals.

But if you keep freshwater dwarf shrimp and other animals that need non-standard water conditions then you may need to mix your own GH and KH blends to meet their needs.

By the way, I go into greater detail on how to understand water chemistry in my article here on how to raise ph in freshwater aquariums.

How Often to Add Salt to Freshwater Aquariums

Lastly, let’s take a moment to talk about aquarium salt in freshwater fish tanks. Because believe it or not, aquarium salt is something I recommend keeping on hand.

Aquarium salt is a tonic that helps fish regulate the flow of ions across their skin and gill membranes. It stimulates healthy slime coat production and is an excellent antiparasitic and antibacterial remedy for diseases like cotton wool disease.

But we need to be careful with using aquarium salt because freshwater fish do not need very much of it at all (except for mollies, which love aquarium salt – even full saltwater).

How Much Salt Should I Put in My Freshwater Aquarium?

As a general tonic, one tablespoon per 5 gallons is enough for most aquarium fish. Be sure to look up the requirements of your specific fish. Tetras and other soft water fish are so sensitive that I don’t recommend using aquarium salt at all with them unless you are treating a specific disease. In which case, a salt dip can help.

But only add salt to aquarium water when performing a water change; don’t add it to water that’s being used to top off a fish tank. This is because salt, like other minerals, does not leave a fish tank when water evaporates.

It simply becomes more concentrated over time. It is only removed during water changes so you can also add it whenever you top off the tank with fresh water post-change.

What Kind of Salt for Freshwater Aquariums?

Make sure to use specifically aquarium salt; the iodine and anti-caking agents in table salt are not at all helpful to freshwater aquarium fish. If you want you can use marine aquarium salt formulas. But it is a lot more expensive, comes in huge amounts, and does not offer any real benefits to freshwater fish.

What Should My Freshwater Aquarium Levels Be?

And speaking of water changes…I always aim to keep my aquarium topped off right near the top of the glass tank. I don’t let much more than an inch of water ever evaporate from an aquarium.

Why? Because as water evaporates the minerals and chemicals it contains remain behind. This causes the concentration of chemicals to rise, which affects your fish.

Since water chemistry swings aren’t healthy for fish it is best to keep your tank topped off with mineral-free water so the chemistry remains stable over time.

Step 6: Dealing with Algae

Even if you have the fish species chosen, aquarium setup and cycled, and your water chemistry fully figured out, there will always be algae to consider. Algae is a fact of life for all aquarium setups. So how do we deal with algae in all of its many forms?

Is Green Algae Good in a Freshwater Aquarium?

Green algae is never a bad thing; in fact, algae of any kind is a sign of life. Algae provides food for algae eaters like plecostomus and mollies. And grazing areas for baby fish and snails. It is only when algae gets out of control that it should be thought of as a problem that needs to be eliminated. 

While it can be scraped away from your aquarium glass to avoid being a detriment to your viewing experience we rarely want to eliminate all algae from your freshwater aquarium. Though if you want some help, you should consider my article here on what is the best algae eater in freshwater aquariums.

What Causes Green Algae in Freshwater Aquariums?

If you are seeing too much green algae growth then there is an imbalance somewhere. Almost always the problem is being caused by too much light, nutrients, or both. Nutrients can come from fish poop, leftover food, or a rich substrate.

And too much light might be lights that are left on for too long, are very high intensity, or of a spectrum that your live plants don’t make optimal use of. All of these matter because if you have live plants then they need the right kind and amount of light to suck up the nutrients that algae would normally use. If your light is poor quality then your plants can’t compete very well with algae, which is much hardier and flexible than complex plant life.

What Causes Red Algae in Freshwater Aquariums?

Red algae is a little different and unfortunately, more problematic. Some red algae is quite beautiful, especially red saltwater macroalgae. But in freshwater aquariums we usually have to deal with black beard and staghorn algae.

Both of these types are ignored by most algae eating fish because they are bitter or even poisonous. Red algae is usually caused by improper amounts of carbon dioxide, lights, and nutrients. They are a sign that your aquarium plants aren’t getting the nutrients they need and can’t compete with the red algae growth.

More Frequently Asked Questions about How to Start a Planted Freshwater Aquarium

Sometimes when setting up a new fish tank people want to talk about plants as well. Since freshwater aquarium plants aren’t for everybody I left them out of the main guide. But what if you want something a little more advanced to start?

How to Start a Planted Freshwater Aquarium

A planted freshwater aquarium is actually an extremely involved project that is very different from a fish only tank. It involves understanding what sort of lights plants need as well as carbon dioxide and other nutrient flows that fish only aquarium systems don’t require. That’s why I go into the fine details right here in my guide on how to start a planted freshwater aquarium.

How to Plant Freshwater Aquarium Plants

In order to plant freshwater aquarium plants, you need to be careful with the roots. Plant them gently to avoid crushing them; bruised roots can rot, which usually results in death. And once you have fully planted them avoid the temptation to move them around every so often. Plants hate being moved and it causes them a lot of stress, which can also lead to weakening, melting, and death.

Final Thoughts

Keeping freshwater aquarium fish can be an extremely rewarding and enjoyable hobby – but it definitely comes with a good amount of work. Though this complete guide, you should be able to choose a great beginner fish and set up your tank the correct way.

Good luck and happy fish-keeping!

Jason Roberts
About Jason Roberts
Jason is an aquarium fanatic that has been a fish hobbyist for almost three decades.

2 thoughts on “50 Best Freshwater Aquarium Fish: The Complete Species Guide”

  1. Thanks.
    I have a Convict Cichlid. He is the lone survivor. As you say, he does tend to kill his neighbors.
    I’ve had him or her about 5 years or more. I may try another Cichlid to keep him company.
    Maybe not.

    Thanks for the great article. It was fun to read. I learned a lot!

    • Hi Terry, thanks for the kind words! Convict Cichlids have a special place in my heart since it was the first species I ever kept. The albino varieties are very interesting as well!

      Unfortunately, I never had much luck keeping them with other fish – my large male didn’t take too kindly to anything I tried to keep with him (even females). As you said though, many people have had success keeping other large cichlid species.

      Good luck!



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