Arowanas are fish occasionally seen in public aquariums, Asian restaurant tanks, and pet stores across the world.
While they start off small, these intriguing, gangly little fish can grow several feet in length and will eat you out of house and home.
They may also pick off their tank mates along the way if you aren’t aware of just how big and hungry these predators get!
When given space Arowanas aren’t especially difficult to care for.
However, space is the main reason these fish are considered Moderate in difficulty; not only do they need turning room but these fish can jump like no other.
If you’re looking for something stately and fascinating to watch, do read over our Arowana species guide:
|Common Name||Arowana (Silver, Black, Asian, Australian), Dragonfish, Monkeyfish|
|Scientific Name||Osteoglossum and Scleropages sp.|
|Color||Variable; Silver to shades of Red and Gold|
|Diet||Carnivorous; Live Prey Preferred|
|Suggested Tank Size||240+ Gallons|
|Water Temperature Requirements||75-83°F|
|Temperament||Predatory but Non-Aggressive|
- Scientific Name: Osteoglossum and Scleropages sp.
- Temperament: Predatory but Non-Aggressive
- Care Level: Moderate
- Origin: South America, Southeast Asia, Africa, Australia
- Common Names: Silver/Black/Asian/African Arowana, Dragonfish, Monkey Fish
As a whole, Arowanas are quite tolerant of other fish so long as they can’t eat them. Even tank mates that may be in the danger zone size-wise can go ignored so long as the Arowana is well fed and used to having them around but its not a safe bet.
Other large fish will be safely ignored; while fast and graceful, Arowanas don’t have the build of a true bully. They will push for their fair share when it’s time to eat but generally save their aggression for other Arowanas.
Arowanas are also great tankmates for other aggressive or predatory fish. Not only will they eat the same live prey but keep to the upper and middle areas of the water column.
Thanks to their tough scales, they can fend off attacks from truly aggressive species like cichlids with relative ease.
Arowanas are tropical predators that come from the near-Equatorial regions of Southeast Asia, Indonesia, Australia, South America, and Africa.
They prefer slow moving rivers that wind through forests; rivers that regularly flood forested areas like the Amazon and Orinoco are prime Arowana habitat.
The shade provided by overhanging branches provides cover as these fish are midwater and surface dwellers, which exposes them to other predators.
Arowanas are ambush predators; they usually capture fish from below and will snatch small reptiles, birds, insects, and other creatures at the water’s surface. Even animals climbing on branches near the water’s surface are in danger as Arowanas will leap to snatch prey.
Being surface dwellers, they are less concerned with substrates compared to other fish. They do prefer plants for occasional cover but are prone to bowling them over in the tight confines of aquariums.
The natural tannins found in their native habitats tends to turn the water not only acidic but tea-colored, which provides a measure of cover for them.
The true lifespan of captive Arowanas is somewhat difficult to know for certain but estimates range from 10-15 years.
Occasionally, individuals are known to live as long as 20 years in ideal conditions.
Arowanas generally reach an adult length of 30-36″, with the Pirarucu growing to a gigantic 7-12 ft. While some fish remain small for an extended period, Arowanas are not only voracious eaters, they grow quite quickly.
Healthy Arowanas can grow as fast as 2″ a month, reaching full size in less than 2 years.
Baby Arowanas, particularly Silver and Blacks, are usually sold around 4″ in length and have a fragile yolk sac from which they draw nutrition.
Over the course of weeks, the yolk sac will eventually be absorbed but beware as it can make a tempting target for nippy tankmates.
Arowana care is straightforward but there are a few basic care requirements you should be aware of:
Captive-bred Asian Arowana are not too picky when it comes to water conditions. Since most other Arowana species are wild caught, though, it’s better to stick to the conditions they find in nature.
When testing the parameters of your aquarium water, you’ll want to be shooting for:
- pH: 6.0-7.0
- Temperature: 75-83°F
- Alkalinity: 1°-8° dKH
These fish come from slow-moving tropical rivers and prefer warm, acidic waters. Arowanas are not overly sensitive to water chemistry.
However, cleanliness is a major challenge when keeping any large predatory fish because they not only eat a lot but they also poop just as much.
This places a heavy load on the filtration and biological processing capacity of your aquarium.
Ammonia and nitrites can easily get out of control, making regular water changes and testing crucial. Every time I need to check on water quality, I prefer using the API Freshwater Master Test Kit to cover all my bases!
Live prey is what Arowanas prefer and lots of it. Prey type isn’t too relevant; insects like moths and crickets, guppies and goldfish, crushed snails, ghost shrimp and crayfish are all acceptable.
Gut-loading live prey with nutritious pellets and flakes gives them a nutritional boost before feeding to your Arowana.
If you train them when young, Arowanas can be trained onto a diet of fresh meat. Beef heart, chopped chicken, and either whole dead fish or slices of fresh fish will be consumed readily if already conditioned onto dead prey.
Many companies like Hikari produce high protein carnivorous fish pellets. But if your Arowanas are wild-caught or used to live prey, it will be very difficult to get them to accept pellets as food.
Arowanas are generally not sociably towards one another. If you really want a small group of Arowanas its best to raise them together at a young age so they’ll become accustomed to one another.
This means keeping them in the very largest of aquariums, of course.
Arowana Types – Common Species
Arowana exist on the tropical portions of continents worldwide: South America, Australia, Africa, and Asia all have native species.
However, only four of those are likely to be encountered in stores with a fifth sometimes available through special order.
Here are the most common Arowana types:
Silver Arowanas are arguably the most commonly found Arowana species in the pet trade.
Which is unfortunate because the majority of aquarists have no ideas these intriguing fish will eventually grow up to 3 feet long.
Hailing from the Orinoco and Amazon basins of South America, these fish are found in forested river channels where they can stalk prey from the surface.
As obligate predators, Silver Arowana can be trained onto meat and dead prey but much prefer small fish, insects, shrimp and crayfish.
Adults are excellent jumpers and can clear the water by up to 6 feet in order to snatch birds and reptiles from tree branches!
Unfortunately, their surface dwelling habits and their inclination towards jumping when startled also makes them prone to ending up on the floor of your living room.
Tight fitting lids are a must, especially when dealing with a 3 foot, possibly 10 lb Arowana!
- Scientific Name: Osteoglossum bicirrhosum
- Size: 36″
- pH: 6.0-7.0
- Temperature: 75-83°F
Amazonian Black Arowanas are nearly as common as Silver Arowanas in the pet trade.
Usually sold as young with a highly visible yolk sac attached, they have distinctive black stripes that eventually fade with maturity. They do retain black fins but are mostly silver in color as adults.
Black Arowanas have identical care requirements to Silver Arowana, including a love for live prey and a willingness to jump at the slightest provocation.
- Scientific Name: Osteoglossum ferreirai
- Size: 36″
- pH: 6.0-7.0
- Temperature: 75-83°F
Asian Arowana, also known as Pearl Arowana, are the second most common species to find their way into aquariums.
Despite being an endangered species in the wild, they are raised by the thousands in farms across the tropical regions of Asia.
These fish are incredibly popular as symbols of good fortune in China, Taiwan, and Southeast Asia.
In fact, one of the most expensive aquarium fish ever sold was a Platinum Asian Arowana, valued at USD$400,000. The Red and Golden varieties are the most popular in the trade.
A number of related Scleropages species can also be found in scattered areas of Myanmar and Indonesia but are almost never encountered in stores.
Thanks to captive breeding efforts, Asian Arowana come in a variety of intriguing color morphs like Super Red and Moonlight Silver.
- Scientific Name: Scleropages formosus
- Size: 36″
- pH: 6.0-7.0
- Temperature: 75-83°F
Found throughout Northern Australia, New Guinea and Indonesia, the Australian Arowana is the least commonly found of the four main species.
Like all Arowana, they need spacious tanks with tight fitting lids to keep them from taking flying leaps.
There is a second Australian species, Scleropages leichardti, that’s even rarer. Known as the Southern Saratoga, this second Arowana is found only in a small stretch of coastal Northeastern Australia.
Like the closely related Asian Arowanas, all Scleropages sp. are noticeably chunkier than their South American cousins.
- Scientific Name: Scleropages jardinii
- Size: 24-36″
- pH: 6.0-7.0
- Temperature: 72-80°F
While fairly rare in the hobby, it’s possible for a persevering Arowana owner to own one of the largest freshwater fish on the planet.
Arapaima gigas, also known by the Amazonian Amerindian name of Pirarucu, is a legendary animal. Capable of growing to at least 10 feet and possibly longer, these fish have specialized armor-like scales that can deflect teeth and spears alike.
All of the Arapaima species are closely related to the Arowana, although the jury is still out whether they share a family or not.
Current thinking is that both the Arapaima and African Arowana are in a closely related but separate group: the Arapaimidae, with the Silver, Asian, and Australian Arowanas more closely related to each other in the group Osteoglossidae.
Regardless, both families are similar in nearly all ways. Mature Pirarucu are, thankfully, far too heavy to jump. But they share their opportunistic habits, taking fish, small mammals, reptiles, and birds from the water’s surface.
They are also partial air breathers and need to take loud gasps every 10 minutes or so from the surface.
Considering their rarity and adult size, Pirarucu are not a casual purchase.
Only aquarists with access to large, tropical ponds (or aquariums the size of swimming pools) and massive amounts of food should consider keeping one of these stately megafish.
- Scientific Name: Arapaima gigas
- Size: 7-12 ft.
- pH: 6.0-7.0
- Temperature: 75-83°F
Arowana Tank Mates
Tankmates for Arowana are not to be chosen lightly. The main danger is from being eaten: Arowanas are opportunistic predators and will consume anything they can fit into their surprisingly large mouths.
Anything that can’t be eaten should be safe, however.
Arowanas are mildly territorial but usually more towards other Arowanas. They tend to ignore other species and have hardened scales that deflect the attentions of even aggressive tankmates.
Their tendency to hang at the surface also places them above the notice of most large fish which prefer the mid and bottom levels of the water column.
Many aquarium fish that are often sold as babies are actually great tankmates for Arowanas as adults. Plecostomus are not only even better armored but can grow up to 2 ft. in length.
Oscars, Green Terrors, Peacock Bass, and other large cichlids are not only predators but aren’t capable of harming Arowanas. Pacu, Silver Dollars, and other large, schooling characins are South American natives that get along splendidly with Arowanas.
Suitable Tankmates for Arowana
- Large Cichlids
- Adult Plecostomus
- Red-tailed Catfish
- Silver Dollar
Tankmates to Avoid
Unfortunately, the list of fish to avoid keeping with Arowana is quite large:
- Smaller Fish: Even tank mates that have lived safely with an Arowana for months are eventually going to be eyed as potential meals once they can fit into its mouth. And Arowanas grow quickly for such large fish!
- Other Arowanas: Arowanas are territorial and intolerant of other Arowanas. There are ways to induce them to live in groups in aquariums. However, it’s much better to keep groups in ponds or pools, to give them enough space to spread out their aggression.
Setting up an Arowana Tank
Here I’d like to discuss what goes into setting up an Arowana tank beyond water quality and parameters.
Arowanas don’t have any particular needs beyond space when it comes to setting up a new aquarium for an adult.
Unfortunately, most new 4″ baby Arowana owners aren’t aware that these fish will outgrow almost any aquarium and will eventually eat their tankmates. Follow these guidelines as your Arowana grows to ensure it remains healthy.
Having the right size tank is the most challenging part of keeping an Arowana. Most species can reach 3 ft. in length, meaning you should have a tank at least half again as wide for them to turn around in.
The bare minimum would be 240 gallons for an adult, with larger being even better.
Arowana are often kept in outdoor ponds or indoor pools, which not only give them plenty of space to turn but even the freedom to jump! Think carefully even on purchasing a baby.
They start small but grow quickly, approaching their maximum size within two years!
Hailing from tropical, flood-prone rivers, Arowanas don’t care much for current, especially at the water’s surface where they frequently watch for prey. It’s better to avoid powerheads and direct the outflow of filtration units in a way that won’t challenge them.
Young Arowanas also have a dangling yolk sack that’s especially vulnerable to being damaged against decorations in swift current.
As inhabitants of the middle and upper water column, Arowanas aren’t concerned with what sort of substrate gets used.
Many keepers of large fish even use bare bottom tanks for Arowanas, cichlids, and other predators. If you’re looking to keep live plants, however, your substrate choice should be one best suited to the needs of these plants.
Adding Live Plants
If you decide to keep live plants along with Arowanas you should aim for the extremes: plants too large or firmly rooted to be knocked about or too small to be easily reached.
Large plants that are too large to be easily knocked about once established include:
- Amazon Swords
- Java Fern
- Anubias sp.
- Vallisneria sp.
- African Water Fern
Small plants suitable for the bottom or attached to driftwood and rocks include:
- Chain Sword Plants
- Dwarf Cryptocoryne
- Java Moss
While predatory fish provide plenty of organics in the form of copious waste, providing inorganics like iron and potassium is often a challenge.
Plants often struggle to grow in newly established tanks as well. Root tablets like these from API help give plants a solid boost in growth if your substrate is unable to retain nutrients.
Driftwood is a nice addition for larger aquariums and pools. But it can crowd out much needed swimming space if the tank is on the smallish side.
Arowanas are not especially concerned about strong aquarium lighting; it’s far more important if you intend to keep live plants along with them.
Moderate to dim lighting is actually preferred due to their tendency to live near the surface.
The tannin-stained waters of their home rivers also tends to be dark, helping cut down on the amount of sun they normally get.
If this is your first time cycling a new tank, have a look at our complete guide to the fishless cycle for a total breakdown on how to safely go about the process of establishing a bacterial bioload.
When setting up a tank for predatory fish, a healthy microorganism population is very important because these fish create tons of waste.
Ammonia levels can quickly get out of control, reaching fatal levels if not dealt with. I prefer using cycling bacteria such as Tetra SafeStart Plus to help jump-start the process.
Breeding Arowanas is even more of an undertaking than keeping them happy in aquariums. Once again, the size of these fish makes their care challenging.
They take years to reach maturity, are picky when it comes to choosing a mate, they have a lengthy courtship period, and they need space to avoid killing one another.
Arowana Breeding Setup
Outdoor ponds in tropical regions of the world are how most captive-bred Arowanas are born. Fish farms in Southeast Asia and South America can operate year-round thanks to the high heat and mild to unchanging seasonal temperatures.
If you live in North America, Europe, and other areas of the world, breeding Arowanas in the outdoors is difficult to impossible without some sort of supplemental heating.
Breeding Arowanas in aquariums is possible but as much a matter of luck as skill.
Determining the Gender of Arowanas
Arowanas are sexually dimorphic (males and females look different) but it’s not as easy as you might hope. For starters, they don’t reach sexual maturity until around 5 years of age.
Males are not only larger but have flowing crests to their fins that give them a more regal appearance compared to females.
Allowing groups to naturally pair off in pools or ponds is the safest, surefire way to get a mated pair of Arowanas.
Inducing Your Arowanas to Spawn
Kept in groups of 6-10 in outdoor ponds, Arowanas are first allowed to naturally pair off before breeding. They won’t always choose the mates provided for them and reliably sexing Arowanas is difficult even for experts.
They are also provided ample amounts of live prey to encourage them to produce eggs and sperm.
Due to their size, aggressive habits, and long courtship period, Arowanas rarely breed in aquariums.
One way to do so is to raise them when young together so they are less likely to see each other as intruders once reaching adulthood. Another way is to introduce two adults into a neutral aquarium with dividers.
After a month of growing accustomed to each other’s presence, remove the divider and carefully observe the two to see how they interact.
If responsive to one another, the female and male court each other over the course of 1-2 months, circling, displaying with fins, and nipping at each other to encourage the production of eggs and sex hormones.
Once this process begins, you’ll want to increase their food rations. The female needs the nutrition for producing eggs while the male won’t eat for around 6-8 weeks after spawning, for reasons outlined below!
Caring for Arowana Eggs
If you’ve actually managed to get your Arowanas to spawn, then congratulations, because for you, the hard part is over! The father’s work, on the other hand, is just beginning.
The eggs are impressively large, around ½” in size apiece. Once the pair lays and fertilizes their eggs the male Arowana swiftly turns and scoops them up into his mouth.
While it may look like he intends to eat them, Arowanas are actually mouth brooders and extremely attentive parents.
Mouth brooding is also used by African cichlids and other fish as a means of defense for the eggs and young. They can be carried around without predators easily threatening the defenseless young. And the eggs receive a constant flow of fresh, oxygenated water.
Once the male scoops up the eggs, the female turns aggressive, attempting to bite and chase him off. At this point, one of the pair should be removed for his safety.
During the mouth brooding period, the male won’t eat at all until the eggs hatch and has a strongly reduced feeding response while the fry are free-swimming. It is imperative he has ample fat reserves to see him through this period of 6-8 weeks.
Young Arowana Care
Once again, the male Arowana does most of the work, carrying the eggs until they hatch. Young Arowanas are quite large, around 2″ in length, and won’t eat immediately.
They also rarely stray from the safety of their father and will hang in a cloud around his head, only to disappear into his mouth when threatened.
As they begin to absorb their yolk sac over the course of 2 months, they will not only grow bolder but eventually take guppies and other small prey items.
Once the yolk sack is mostly gone (3-4″) and they reliably take live prey items, you can separate them from their father.