15 Compatible Plecostomus Tank Mates

Hypostomus plecostomus, the Common Pleco, is one of the most popular aquarium fish in the world. They are sold when small as algae eaters and are excellent at the task while being fascinating to watch.

However, few aquarists realize Plecostomus can grow to be massive (18-24 inches) and are often territorial as they grow up. These tank-like vegetarians don’t have the teeth to do much harm to intruders but can still make life difficult for bottom dwelling tank mates.

You should choose companions that won’t try to steal their favorite hiding spaces. Here are the 15 best Plecostomus tank mates perfect for long-term compatibility!


Upper Water Plecostomus Tank Mates

Any fish that prefers this area of the aquarium should be a great tank mate for your Pleco. As bottom dwellers Plecostomus rarely patrol this zone save for the occasional gulp of air (Plecos are facultative air breathers and can supplement with atmospheric oxygen).

Hatchetfish

Hatchetfish make excellent tank mates for Plecostomus because the two species will rarely encounter each other. Hatchetfish evolved to sit directly under the water’s surface while Plecos hug the bottom of the tank.

The two fish are also opposites in terms of feeding habits. Hatchetfish pick up floating insects and plankton from the water column and need a diet of flakes, tiny pellets, and small foods like Brine Shrimp Nauplii.

Peaceful and schooling, their unusual appearance, ease of care, and handsome patterns make Hatchetfish good additions to most community tanks. Take your time when introducing them to aquariums with radically different parameters as they can be sensitive to sudden shifts in water conditions.

While Hatchetfish may be startled by your Pleco rushing to the surface for a gasp of air they are a great match. As fellow Amazonian natives they also prefer the same tropical, acidic water conditions as Plecostomus.

  • Scientific Name: Gasteropelecidae family
  • Origin: South America
  • Size: 2 to 4 inches
  • Temperament: Peaceful; Schooling
  • Special Notes: When startled Hatchetfish glide along the surface and can actually fly short distances thanks to their well developed pectoral muscles and fins. A tight fitting lid is a must.

Arowanas

Arowanas are surface dwelling predators that pick off other fish, insects, and even small reptiles and birds that swim along the surface of rivers. They aren’t safe even if they’re in branches or in the air. Arowanas have excellent eyesight and can leap up to 6 feet to pick off small prey.

Their ability to leap means well secured hoods are a must; a startled 3 foot adult will easily bust past the lid of most aquariums. Arowanas can often be bought as 4 inch juveniles with yolk sac still attached.

They are ravenous, however, and will outgrow (and eat) most of their tank mates within their first year of life. Plecostomus are too large, spiky, and out of their hunting region to be of much interest, though.

Arowanas are hardy but produce a lot of waste, making a powerful, mature filter and frequent water changes essential to their long-term survival.

If you’re interested in learning more about this fascinating family of fish, my Complete Arowana Fish Guide is a great place to start!

  • Scientific Name: Osteoglossidae family
  • Origin: Worldwide
  • Size: Up to 4 feet
  • Temperament: Semi-aggressive; Predatory
  • Special Notes: At $400,000, an Asian Arowana was the world’s most expensive aquarium fish ever sold!

Danios

While quite a bit smaller than even a young Plecostomus Danios are excellent tank mates for them. They keep to the surface and midwater areas and are peaceful, schooling fish that rarely bother other fish.

Danios as a group are hardy and inexpensive fish. Zebra Danios are extremely popular as are Pearl and Giant Danios. Most species are found in tropical regions of South Asia but can also be kept in unheated tanks with temperatures down to 65-68F.

Danios are especially easy to breed as well, scattering their tiny eggs across plants and other decorations. The vast majority of them will likely be eaten by your Plecostomus but a lucky few may hatch and grow up to join the school!

  • Scientific Name: Danio species
  • Origin: South Asia
  • Size: 1 to 6 inches
  • Temperament: Peaceful; Schooling
  • Special Notes: Danios should always be kept in schools of 6 or more.

African Butterflyfish

Closely related to the Arowana family, the African Butterflyfish is a dwarf species that occasionally is found in the trade. While they sport a camouflage pattern they stay right at the water’s surface, patrolling for small fish and fallen insects.

Like their larger cousins African Butterflyfish are excellent jumpers when startled. However they are great for aquariums as small as 20 gallons since they don’t grow much larger than 4 inches.

Be careful when choosing tank mates for African Butterflyfish because while peaceful they are predatory and have surprisingly large mouths. Guppies, Tetras, and other slim fish will eventually be eaten.

While semi-aggressive towards other surface dwelling fish they will rarely ever interact with bottom dwelling Plecostomus. They can be trained to eat prepared foods but absolutely love small insects like flies and crickets!

  • Scientific Name: Pantodon buchholzi
  • Origin: West Africa
  • Size: 4 inches
  • Temperament: Semi-Aggressive; Territorial; Predatory
  • Special Notes: Like Hatchetfish and Arowanas, African Butterflyfish are born jumpers; a secure hood is essential!

Pencilfish

Like Plecostomus Pencilfish come from South America and love tropical temperatures (78-84F) and soft, acidic conditions (pH 6.0-7.0). Unlike Plecos they are small, schooling fish that eat tiny invertebrates and plankton.

Thankfully, Pencilfish are very un-picky about their food and will also take small pellets and flakes as well as Brine Shrimp Nauplii, Daphnia, and other live or frozen offerings.

They may even breed for you, but this usually happens in heavily planted aquariums with water parameters matching the above conditions.

There are roughly 19 species and they are often sold interchangeably. Pencilfish have a subtle pattern of golds, reds, and brown tones over a white belly but all are attractive and easy to care for!

  • Scientific Name: Nannostomus species
  • Origin: South America
  • Size: 2 inches
  • Temperament: Peaceful; Schooling
  • Special Notes: Pencilfish are ideal inhabitants for nano planted aquariums!

With their tiny mouths they need food suitably sized for them, such as mini or micro pellets. These floating prepared options are also good for Tetras, Hatchetfish, and other small surface dwellers.

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Mid-Water Plecostomus Tank Mates

The middle of the water column is the most diverse zone. Fish from all levels come here and a few species spend nearly all of their time here.

The main issue is to avoid large, peaceful, slow-moving fish with broad bodies. Plecostomus are known to occasionally latch onto slower fish to snack on their nutritious mucus as they get lager. This rasping is stressful and genuinely harmful because it exposes fish scales and skin to infectious agents.

Many other large suckermouth fish like Chinese Algae Eaters also have this habit. Fish like Discus, Gouramis, and Goldfish should not be kept with larger Plecostomus. Instead choose fast, schooling fish or tank mates that will nip back if provoked!

Glass Catfish

Glass Catfish are some of the most interesting fish in the hobby because they break nearly all of the Catfish rules. Rather than being single, somewhat fat, slow moving bottom dwellers they are slender, highly active schooling fish that swim in the middle of the aquarium.

Similar to Ghost Shrimp, they also have a special form of camouflage: near-transparency! Glass Catfish are almost perfectly see-through and you can easily see their spinal column through their glass-like skin and muscles.

Their body cavity is pigmented to prevent UV from damaging their organs and their eyes need pigment to catch light. However they are nearly invisible to predators in most settings and hard to track when moving fast in a group.

Glass Catfish are carnivorous and live protein-rich prepared and frozen foods like Bloodworms and Tubifex. They also aren’t shy about fighting for their share at the surface. These Catfish should always be kept in groups of at least 6 and need a tank at least 30 gallons in size.

  • Scientific Name: Kryptopterus vitreolus
  • Origin: Thailand
  • Size: Up to 5 inches
  • Temperament: Peaceful; Schooling
  • Special Notes: While generally peaceful, Glass Catfish will eat tiny fish like young Guppies and Tetras.

Tiger Barbs

Tiger Barbs are popular for good reason. They are broad, showy fish that dominate the middle of an aquarium with their activity and bold nature. Tiger Barbs also come in several color varieties, including Albino and Green morphs.

Tiger Barbs have been captive-bred for decades and accept a wide range of prepared and fresh foods as well as most aquarium water conditions. In their homelands they are found in soft, acidic waters that are very warm (78-84F) and these conditions often bring out better color and breeding responses.

While fairly peaceful Tiger Barbs can grow a bit too curious about slow moving fish with long fins. Bettas, Gourami, and Goldfish may find their fins being constantly nipped and creating routes for infections like Fin Rot. However, Plecostomus rarely have issues with Tiger Barbs.

  • Scientific Name: Puntigrus tetrazona
  • Origin: Southeast Asia
  • Size: Up to 4 inches
  • Temperament: Peaceful to Semi-aggressive; Schooling
  • Special Notes: Keep Tiger Barbs away from long-finned fish like Bettas.

Cichlids

While Cichlids in general tend to be broad bodied fish they are mostly semi-aggressive to aggressive and won’t put up with a pushy Plecostomus looking to attach to their flanks.

Discus and Angelfish are a poor match but nearly all other Cichlids work well with them. Plecos are ideal scavengers and algae eaters for tanks containing large, aggressive species like Jack Dempseys, Flowerhorns, and even Jaguar Cichlids. A Pleco’s heavy scales and spiny fins are excellent protection for the angry moods Cichlids sometimes (or always) fall into.

While Plecos are tolerant of most water conditions they prefer soft, slightly acidic waters. Other South American Cichlids like Severums, Green Terrors, and Oscars also prefer these conditions.

  • Scientific Name: family Cichlidae
  • Origin: Worldwide
  • Size: Variable
  • Temperament: Mostly semi-aggressive to aggressive; Territorial
  • Special Notes: Some Cichlids can become too aggressive even for Plecostomus when breeding!

Silver Dollars

While they fit the profile of large, broad bodied fish, Silver Dollars are fast, schooling fish that won’t get caught by a hungry pleco. They are also quite peaceful and excellent dither fish for aquariums with large Cichlids and other single showpiece specimens.

While they are beautiful, keep Silver Dollars away from planted aquariums! They are cousins to the ravenous Piranha, only vegetarian, and will reduce even the toughest aquarium plants to nubs within weeks.

Both Silver Dollars and Plecostomus will be lining up to munch on blanched vegetables like cucumber and cauliflower, as well as Spirulina-based prepared foods. So make sure everyone gets their fair share when feeding.

Since they are also found throughout the Amazon Basin both Silver Dollars and Plecostomus do well in tropical, slightly acidic waters with plenty of driftwood and other tannin-releasing agents.

  • Scientific Name: Metynnis species
  • Origin: South America
  • Size: Up to 8 inches
  • Temperament: Peaceful; Schooling
  • Special Notes: They are schooling vegetarians related to both Neon Tetras and Piranha

Livebearers

Although Sailfin and Yucatan Mollies can top 6 inches, most Livebearers are on the small side. However they are thin, peaceful fish that are model community tank residents.

Livebearers come in hundreds of dazzling color forms, with Guppies perhaps being the most diverse of all! They are all also incredibly easy to breed; so long as your water conditions aren’t actively toxic you’re guaranteed to see babies eventually swimming about.

While Mollies are notably vegetarian most Livebearers are omnivores and should be fed a mixture of fresh and prepared foods as well as occasional greens and frozen meaty treats.

While they prefer hard, alkaline water conditions, keeping your aquarium as close to neutral as possible (pH 7.0) will satisfy both Livebearers and Plecostomus!

  • Scientific Name: family Poeciliidae
  • Origin: North & South America
  • Size: Up to 6 inches
  • Temperament: Peaceful
  • Special Notes: Livebearers produce fry almost continually when established and happy but will eat them unless they are given shelter.

Bottom Dwelling Plecostomus Tank Mates

The substrate level of the aquarium is where you will run into the most issues when choosing Plecostomus tank mates because this is where they spend all of their time.

While generally peaceful many Plecos do become territorial as they age. And if they find or are given a cave or nook in a piece of driftwood they will put up a fuss if another bottom dweller tries to force their way in.

That said, here are some Plecostomus tank mates for the bottom of your tank!

Hoplo Catfish

If you take a Giant Corydoras and stretch it out you’ll end up with something like a Hoplo Catfish. These near cousins to Corys reach about 8 inches in size and have armor comparable to a similar sized Plecos.

Another reason Hoplo Catfish are great tank mates for Plecostomus is that they frequent all levels of the water column. Even if a Pleco decides to push around a Hoplo Catfish, it will simply wander around the middle or even upper levels of an aquarium. They are active, engaging Catfish that will be at the front of the glass dancing for food along with the other residents.

While Hoplo Cats are opportunists they have tiny mouths and only the smallest of fish fry or eggs are in danger of being eaten by them. They are also very peaceful and tolerant of a wide range of water conditions.

They will snack on the same sinking pellets as Plecostomus, though, so ensure you offer enough for both species!

  • Scientific Name: Megalechis thoracata
  • Origin: South America
  • Size: Up to 8 inches
  • Temperament: Peaceful
  • Special Notes: Hoplo Catfish are bubble nest builders, similar to Bettas, and the male dutifully guards the eggs until they hatch.

Pictus Catfish

Pictus Catfish look like miniature sharks and are sometimes called Shark Catfish in the trade. From South America, the Pimelodid family is full of large, fast moving predatory catfish, including the Red Tail and Shovelnose Catfish, both of which can top 2 feet or more.

Pictus Catfish are smaller members of the family but are true predators. While often sold small if they outgrow their tank mates they will happily eat them. Guppies, small Tetras, and Danios are exactly the kind of fish they hunt in the wild.

Fortunately, Plecostomus are far too large and spiky to be of any interest. Pictus Catfish are otherwise peaceful and prefer being kept in groups or schools.

They should be fed a mixture of protein-rich prepared foods and meaty items. Sliced fish, chopped beefheart and shellfish, live Guppies, and frozen Brine Shrimp cubes are all favorites.

  • Scientific Name: Pimelodus pictus
  • Origin: South America
  • Size: 5 inches
  • Temperament: Peaceful; Predatory
  • Special Notes: A Pictus Catfish’s dorsal fin spine has a mildly venomous sting on par with a bee’s in pain. If stung, immersing the wound in very hot water neutralizes the venom.

Black Ghost Knife Fish

Black Ghost Knife Fish are weakly electric fish found in the same rivers as Plecostomus. They generate a constant field of energy that they use when navigating at night. The field deforms when it contacts obstacles and these adjustments are sensed by the fish.

Knife Fish can also detect the weak emanations from muscle contractions of prey like small fish and worms, silently honing in on sleeping animals in the dark. Normally nocturnal, they can be trained to eat during the day and prefer live and frozen food to prepared options.

While rather large and willing to eat small fish Black Ghost Knife Fish are peaceful residents for larger community tanks. They can reach up to 1½ feet and need a cave or other region to call their own.

Black Ghost Knife Fish can’t outmuscle a Plecostomus and will be stressed if forced out into the open constantly, so ensure both fish have space to hide.

  • Scientific Name: Apteronotus albifrons
  • Origin: South America
  • Size: 1½ feet
  • Temperament: Peaceful; Predatory
  • Special Notes: Females emit higher frequency signals than males and both sexes use their electrical fields for communication.

Spiny Eels

While unusual in appearance Spiny Eels have no difficult care requirements beyond needing very large aquariums once mature. The longest species should be kept in nothing smaller than 120-150 gallons.

Spiny Eels are opportunistic predators with a taste for small fish and worms. Live prey as well as frozen invertebrate cubes are perfect, however they will greedily eat prepared carnivore pellets as well.

Spiny Eels do like to burrow and should be given fine sand substrates; they may also attempt to burrow in gravel but the larger grains can scratch and injure their scaleless skin. Burrowing also helps ensure they won’t compete with Plecostomus for favored hiding places.

I also discuss the Tire Track and Fire Eel, two of the most popular species, in greater detail in my Freshwater Aquarium Eels Guide!

  • Scientific Name: Mastacembelus species
  • Origin: Southeast Asia
  • Size: Up to 3 feet
  • Temperament: Peaceful; Predatory
  • Special Notes: Spiny Eels are master escape artists; aquarium lids need to be very secure and with no holes.

Clown Loaches

Clown Loaches, like Plecostomus, are another large bottom dweller that starts out small and cute. They are also schooling fish and prefer being kept in groups of at least 6, making them best for the largest of aquariums.

Fortunately, there is a good market for adults in need of a new home and baby Clown Loaches are great tank mates for Plecostomus. They are colorful, peaceful, and quite hardy.

As scaleless fish they can be sensitive to strong medications and are prone to infections like Ich and bacterial lesions, however.

In the wild, Clown Loaches are invertebrate hunters and love eating snails, shrimp, worms, and other bottom dwelling critters. While they prefer being fed similar items in tanks they will also eat flakes and pellets with gusto.

  • Scientific Name: Chromobotia macracanthus
  • Origin: Southeast Asia
  • Size: Up to 12 inches
  • Temperament: Peaceful; Schooling
  • Special Notes: Clown Loaches love snails and will wipe out most infestations in a matter of weeks.

When feeding Plecostomus and other bottom feeders, you need food that will reach the substrate quickly before other fish can rob them of their fair share. Sinking pellets that Clown Loaches and other bottom dwellers also love are best here!

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