Otocinclus Catfish

Otocinclus Catfish And Betta Fish: Not Ideal Tankmates

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If you’re starting to see algae in your betta fish tank, you might be considering a few different tank mates to help clean up after your betta. It is important to remember that betta fish are aggressive fish and are often best kept by themselves. However, there are some fish that will do well as betta tank mates, like Corydoras, but this does not include Otocinclus catfish.

Keep reading to find out why members of Otocinclus don’t make ideal tank mates for bettas, and some other fish alternatives that will work better!

About Otocinclus Catfish

Otocinclus is a genus of freshwater catfish that contains 19 different species. These fish live in the well-oxygenated and moderate-flowing waters across the Andes mountain range in South America. They can be found schooling in the thousands, munching on leaves and rocks where algae is growing; most often, these fish are spotted in the upper water column

Interestingly, these fish have adapted the ability to breathe air. If oxygen levels are low in the water, otos will swim to the surface and take in atmospheric air to breathe.

In the community tank setting

In the aquarium setting, otos need a little more care and consideration than most other community fish. Though they only grow to be about 1 to 2 inches (3.8-5.0 cm), otos are active eaters and need plenty of surface area to graze in a school. It is recommended to keep Otocinclus in a well planted and matured tank that is at least 20 gallons (75.7 L) to ensure that there is enough natural food in the system.

One of the main challenges about keeping Otocinclus is that they heavily depend on the algae that is already present in your tank; if your system is relatively new, these fish are not for you! They are relatively picky eaters otherwise and will need to be regularly offered algae wafers and blanched vegetables. It is also important to keep in mind that these fish are very shy and will only do well in a community tank settings with other peaceful fish, like rasboras and tetras.

Can Otocinclus be kept with betta fish?

You might be looking to get something that brings some movement to the bottom of your tank and a species of Otocinclus is at the top of your list. Unfortunately, otos do not make good tank mates for betta fish.

Bettas are aggressive fish and need to be kept on their own when placed in smaller tanks; even females need to be carefully watched for aggressive behaviors. Otocinclus catfish are very shy and will get easily picked on and attacked by a more aggressive betta.

In addition, otos need to be kept in schools and will not be able to be kept in a 10 gallon (37.9 L) betta fish tank due to lack of space. Remember, in the wild, oto catfish tend to favor the upper water column just like your betta and the two will not be able to peacefully coexist in the same region of the tank.

Otocinclus Catfish

Tank conditions

Otos also require a moderate water flow in order to replicate their natural environment. Bettas are easily pushed around the aquarium by higher water currents and will not tolerate the conditions needed for keeping otos happy.

Lastly, most betta fish are known to pick at most plants in the aquarium setting. Since plants grow algae, which is the source for most of the food for otos, your Otocinclus could potentially starve and become stressed out due to a lack of natural hiding spots.

Is Otocinclus good algae eaters?

Otherwise, otos are amazing algae eaters that will keep most algae outbreaks from happening. Some hobbyists even need to lengthen their photoperiod and/or light intensities to promote algae growth in order to make sure that their otos are getting enough food.

Because of their large demand for algae, Otocinclus should never be placed in an unplanted or newly-set up an aquarium.

For a full list of algae eaters that can be kept with betta fish, make sure to check out our guide here!

What fish can you pair with a betta?

Some hobbyists have, in fact, had success keeping Otocinclus with betta fish, though there are definitely better pairings that have higher success rates.

Snails and shrimp

While not fish, some of the best tank mates for bettas include snails and shrimp. Not only will they keep your tank clean and add more movement to the aquarium, but your betta is more unlikely to bother them. Some colorful and peaceful shrimp you could get are cherry shrimp and ghost shrimp and will require little to no extra care or maintenance.

Cory catfish

If you’re really wanting to try keeping another species of fish with your betta, one of the most popular choices is Corydoras, otherwise known as cories or cory catfish. However, these fish will need to be kept in schools and water temperature will need to be monitored as members of this genus do better in cooler temperatures.

We recommend a tank size of at least 20 gallons (75.7 L) to be able to house a school of six of the most betta-compatible Corydoras species, pygmy cories (Corydoras pygmaeus); other species are considerably larger and will most likely need a longer and/or larger tank in order to be kept with a betta.

For other ideas about stocking your betta fish tank, make sure to check out our guide on the top tank mates for betta fish here!

Otocinclus Catfish

What fish can live with bettas in a 5-gallon tank?

None. 5 gallons (18.9 L) is barely enough room to keep one betta, let alone another fish. The most that you can add to a 5-gallon betta fish tank is one snail; shrimp may work, but such a small space will make it easier for your betta to mistake them as food.


While some hobbyists have had success keeping Otocinclus with betta fish, we think that they will do a whole lot better in a community tank with other peaceful species. Otocinclus are shy and need to be given special consideration due to their diet; tank conditions and aquascaping options are also largely incompatible between the two species.

If wanting to get a fish to keep with your betta, consider members of Corydoras or adding a couple of snails or shrimp to the aquarium.

If you have any questions about Otocinclus, other tank mates for bettas, or have had experience keeping bettas with other species, don’t hesitate to leave a comment below!

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