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8 Safe Tank Mates for Upside-down Catfish: Compatibility Guide 2023

Sarah Psaradelis

By Sarah Psaradelis

upside down catfish in aquarium

The upside-down catfish (Snynodontis nigriventris) is a fascinating fish that appears just as the name suggests. The upside-down catfish is part of the Mochokidae family, which contains approximately 100 different species of fish. They are one of the smallest genera of upside-down catfish and swim with an upside-down posture. This makes it easier for this fish to effectively feed off of the surface of the water, which is something that many other species of catfish struggle with because of the mouth placement.

If you already own an upside-down catfish, you’re likely looking for potential tank mates. Let’s check out what some of these are so that you don’t house two fish together that could potentially cause each other harm.

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Top 8 Tank Mates for Upside-down Catfish

1. Congo Tetras (Phenacogrammus interruptus)

congo tetras in aquarium
Image Credit: chonlasub woravichan, Shutterstock
Size 2.5-3.5 inches
Diet Omnivore
Minimum tank size 20 Gallons
Care Level Easy
Temperament Community (Should be kept in groups of 6 or more)

The Congo Tetra is a large species of tetra that is peaceful enough to get along well with the upside-down catfish. They are colorful, peaceful shoaling fish that inhabit all levels of the aquarium, but they prefer the middle level.

The Congo tetra has slightly larger and more flowing fins than other species of tetra, which makes their colors pop against the neutral-toned upside-down catfish. Since they are shoaling fish, it is best to keep them in large groups between 6 to 8 other Congo tetras. They can become skittish and nippy if they are in small groups.

2. Dwarf South American Cichlids (Apistogramma agassizii)

Dwarf South American Cichlids
Image Credit: Arunee Rodloy,Shutterstock
Size 4 inches
Diet Omnivore
Minimum tank size 25 Gallons
Care Level Moderate
Temperament Semi-aggressive

The dwarf South American cichlid is colorful and small growing. Although cichlids have a reputation for being aggressive, dwarf cichlids seem to only be mildly aggressive which allows them to be housed with upside-down catfish with minimal issues. They are found in the tropical rainforests and open savannahs where they inhabit streams and rivers. They prefer quiet backwaters, oxbows, and other slow-flowing bodies of water.

The majority of dwarf South American cichlids are peaceful with fish that will not provoke them, which makes them a good match for upside-down catfish.

3. Zebra Danios (Danio rerio)

danio zebrafish
Image Credit: topimages, Shutterstock
Size 2 inches
Diet Omnivore
Minimum tank size 10 Gallons
Care Level Easy
Temperament Peaceful (should be kept in groups of 6 or more)

Zebra danios are popular in the aquarium hobby because they are so easy to find and their care is simple. They are on the smaller end, so it would be better to only house adults with upside-down catfish. They come in a variety of different colors from green, blue, brown, pink, purple, and red.

The zebra danio does best when kept in groups of 6 to 10, and the more you add to their shoal, the more active and peaceful they will become.

4. Corydoras (Corydoradinae)

Corydoras Catfish
Image Credit: Rethinktwice, Pixabay
Size 2-4 inches
Diet Omnivore
Minimum tank size 20 Gallons
Care Level Easy
Temperament Peaceful (should be kept in groups of 5 or more)

Corydoras are a species of catfish that makes them the perfect tank mates for upside-down catfish. They both have similar care requirements in terms of water parameters, feeding, and tank size.

Corydoras are well-known for their excellent cleaning abilities as they eat algae, leftover fish food, and accumulated debris from various surfaces of the aquarium. Unlike the upside-down catfish, Corydoras cannot eat off the surface because their mouths are small and downturned. However, you can get many different color varieties of Corydoras, with the most common being the albino corydoras.

5. Mollies (Poecilia sphenops)

black molly fish
Image Credit: Kocsis Sandor, Shutterstock
Size 3-3.5 inches
Diet Omnivore
Minimum tank size 20 Gallons
Care Level Easy
Temperament Community (Should be kept in groups of 6 or more)

Mollies are a type of live-bearing fish that primarily feed on algae on the walls of the aquarium. Their upturned mouths are perfectly suited for this job.

Mollies inhabit the fresh streams and coastal brackish waters of Mexico and can handle a slightly higher salinity content than other freshwater fish. However, it is not necessary to add aquarium salt in their captive environments if they live in the same aquarium with salt-intolerant fish like the upside-down catfish.

Mollies are typically peaceful and get along great with different species of catfish.

6. Platys (Xiphophorus maculatus)

Southern platyfish
Image Credit: topimages, Shutterstock
Size 2.5-3 inches
Diet Omnivore
Minimum tank size 20 Gallons
Care Level Easy
Temperament Peaceful (should be kept in groups of 6 or more)

Platys are closely related to molly fish, which are both livebearers. Platies have more prominent fins and colors that add an attractive factor to aquariums with plain-looking fish. Platys also thrive in brackish water conditions, but since the upside-down catfish does not have the same requirement, you do not have to add in aquarium salt to keep them with upside-down catfish.

Platys have fascinating fin shapes, which makes them different than other species of livebearer. If you do not like the bulky and short-finned body of mollies, the platy may be the next best option.

7. Guppies (Poecilia reticulata)

guppies in aquarium
Image Credit: Piqsels
Size 1.5-2 inches
Diet Omnivore
Minimum tank size 10 Gallons
Care Level Easy
Temperament Peaceful (should be kept in groups of 8 or more)

Guppies are colorful and small shoaling fish that are peaceful and great additions to the community aquarium. Since they are small in size, adults are better suited to aquariums with upside-down catfish since this lowers the risk of the guppies being eaten.

Guppies prefer to stay together in large groups, so it is recommended to keep them in groups of no less than 8 fish. This also helps to lower any nervousness guppies may experience by being kept in small groups, which decreases the amount of time you will see them swimming around the aquarium.

8. Elephant Fish (Callorhinchus capensis)

Elephant Fish
Ashera Cat (Image Credit: Devon Bowen. Wikimedia Commons CC BY-SA 4.0)
Size 7-9 inches
Diet Carnivores
Minimum tank size 40 Gallons
Care Level Moderate
Temperament Territorial

The elephant fish can be housed with the upside-down catfish if you have more experience with both species. When done right, these two fish can coexist together with few issues. The elephant fish is seemingly peaceful when kept on its own in an aquarium but can become territorial if other fish try to enter its preferred area of the aquarium. Since they inhabit a different level in the aquarium than the upside-down catfish, they should rarely run into each other.

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What Makes a Good Tank Mate for Upside-down Catfish?

Other catfish, like corydoras, are ultimately one of the better tank mate options for upside-down catfish. Another good tank mate for upside-down catfish is any tropical species of shoaling fish, such as mollies and platys. These fish have a greater success rate when paired with upside-down catfish because they are both peaceful and will not try to provoke one another.

Some of the more advanced tank mates for upside-down catfish are the elephant fish or the dwarf South American cichlid. It is best to only attempt the cohabitation of these species if you can provide a large aquarium with enough plants and hiding spaces so that both fish have places to hide and avoid each other if any aggression and territorial issues present themselves.

panda corydoras
Image Credit: tarzan1104, Shutterstock

Where Do Upside-down Catfish Prefer to Live in the Aquarium?

Upside-down catfish prefer to stay near the top level of the aquarium. This makes it easy for them to eat food from the surface. It can be confusing at first to get used to the appearance of the upside-down catfish, but once you understand how they swim and feed, it becomes easier to not constantly believe that your catfish is upside-down.

Water Parameters

Upside-down catfish are tropical and freshwater fish, which requires a heater and a good source of mechanical, biological, and chemical filtration. Clean water is the key to keeping your upside-down catfish in good health, as these fish are sensitive to levels of ammonia and nitrite above 0.1 ppm.

The nitrate levels can be tolerated in a range between 10 to 20 ppm, but anything higher can start causing nitrate poisoning in your upside-down catfish. It is optimal to ensure that the aquarium has been fully cycled before placing your catfish in, and regular water changes are necessary to keep the water quality good.


Upside-down catfish are small fish that reach an adult size of 3.5 to 4 inches from head to tail. The minimum tank size recommended for this fish is 20 gallons long. It is better to keep a group of upside-down catfish together, with the average group size being between 4 and 6.

Keeping upside-down catfish alone or in pairs can cause them to become stressed because it is unnatural for them. If you do plan to add tank mates into your upside-down catfish aquarium, the size should be increased significantly to comfortably support all the fish.

A good way to calculate the size required for your upside-down catfish and any tank mates is to add 20 gallons onto the minimum tank size requirement for the specific tank mate.

Aggressive Behaviors

The upside-down catfish is rarely aggressive and is known to be rather peaceful and mellow. They can become frantic and stressed if the group is too small or if another tank mate is provoking them. However, they rarely bite and will flee before resulting in fighting the other fish back. This makes it essential to provide them with appropriately sized caves and clusters of live plants so that they have the opportunity to escape any threats.

PH checking solution in aquarium tank
Image Credit: finchfocus, Shutterstock

Top 3 Benefits of Having Tank Mates for Upside-down Catfish in Your Aquarium

  • Having tank mates helps to provide them with enrichment and companionship. This can help make an aquarium feel less empty.
  • Tank mates add color to an aquarium, which upside-down catfish seem to lack. Adding different colors of fish into an aquarium can also make it look more attractive and appealing.
  • Tank mates also add an entertainment factor to the tank. Since upside-down catfish are not overly active, adding in other species of fish can help to increase the activity levels in the aquarium.

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There are plenty of ideal tank mates for the upside-down catfish. Narrowing down your options is a good idea if you want to find the best tank mates for your shoal of upside-down catfish.

All the necessary factors should be considered before you pair new fish with your upside-down catfish, which mainly includes the tank size, food type, water quality, and temperature. It would not be beneficial to keep a cold-water fish with the tropical upside-down catfish, and it would not benefit the other species of fish either.

If you are looking to add a colorful aspect to the aquarium, guppies, mollies, and dwarf South American cichlids can easily provide that.

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