9 Perfect Otocinclus Tank Mates (for Beginner Aquariums)

Otos are a great fish for just about any aquarium. They’re easy to care for and fun to watch zoom around your aquarium.

(When they aren’t glued to your aquarium glass or holding themselves onto a plant with their fins.)

I like them so much they were the second fish I put into my 29 gallon aquarium (after my clown pleco). So I got to wondering, what else can I add to the aquarium with them?

I try to include several unusual choices to keep this list interesting, but most of these fish should be easy for beginners to care for.


If you want a good centerpiece for your aquarium, a betta might be a good option. You’ll want to have an understocked aquarium so that your betta doesn’t feel crowded out, but it makes for a nice looking aquarium.

My Betta in Front of My Ottos | Source: Tiny Underwater | License: CC-BY-4.0

Betta have a reputation for being mean, but my betta has been getting along quite nicely with my Otos. (Even when they are right beside each other in the aquarium.)

That having been said, I’d still limit this type of setup to at least a 20 gallon long aquarium, to make sure there is enough space to keep the betta from getting territorial. A sponge filter would also be preferable to a hang on back filter, due to the fact that betta don’t like strong currents.

Having it well planted (with real or fake plants) and breaking line of sight in the aquarium also can’t hurt.

Clown Pleco

Another good option for a tank mate for your otos is a clown pleco. They have a rather interesting coloration, and they stay small (making them good for smaller aquariums).

Like any pleco, they can be territorial with the bottom of the tank, but it typically won’t be a huge issue with Otocinclus catfish, because they don’t hang around the bottom of the tank much in my experinence.

One potential downside of having a clown pleco is that they’re notoriously shy, so you won’t get a chance to see them much in your aquarium.

They also don’t do a great job of eating algae, though Otos are perfectly capable of doing this job on their own. (For some types of algae, such as brown/diatoms.) The only real requirement is that you have a piece of driftwood in the tank if you’re going to have a clown pleco.


Cory catfish are another good choice. They are peaceful and, while I don’t have them myself, I’m told they’re fun to watch. (Basically the dogs of the fishkeeping world.)

There are a variety of different corydoras in different colors and that can handle different temperatures, tank conditions, and tank mates.

School of Bronze corydoras swimming in aquarium tank,Corydoras aeneus

Like Otos, you’ll want to keep corys in a group of at least 6, as they are a shoaling fish and need a social group.

They also need to be kept in at least a 20 gallon long for best results. They spend a great deal of time on the bottom of the tank, so a longer tank is always going to be better than a narrower but taller tank.


While they can live in aquariums with gravel, they do best in sand. They like to root around in the substrate, and some people believe that gravel might hurt their barbels (whiskers).

Catfish Corydoras in an aquarium close up

If you want more information about them, check out my care guide here.


Rasboras are one of the most popular fish in the industry. Being a peaceful community species, they are another good choice for an aquarium with otos. (Here are some other fish they work with as well.)

Blue Neon Rasbora | Source: Deposit Photos

There are a variety of species, but most should be fine with otos. Here are a few suggestions:

  • Blue Neons
  • Green Neons
  • Harlequin Rasboras
  • Chili Rasboras
Harlequin Rasboras | Source: Deposit Photos

With most varieties of rasbora, you’ll want to keep at least a group of 6. (Preferably larger.) Like corydoras, they are a shoaling fish and need to be kept in a group.


Mollies are another good choice for tank mates for otos. They tend to be a peaceful community fish, though you will want to keep them in at least a 29 gallon aquarium.

Dalmation Molly | Source: Deposit Photos

They tend to eat a lot and produce a lot of waste, and in addition they are livebearers that will produce fry every month, so you’ll want to give them enough room to thrive.

One word of caution with mollies, however, is that they are prone to disease, so you’ll definitely want to quarantine them before you put them into your display tank. Ich especially is a problem for them.

One of the reasons this happens is because they are often bred oversees in brackish water. When they’re moved into freshwater in your local fish store, they have trouble adjusting and take ill.

Because of this, when shopping at the store you’ll want to make sure you get the healthiest mollies you can find. If you can get them from a local breeder, even better.

Sailfin Molly | Source: Deposit Photos

Some mollies, including young ones and ones who have been starved, will even eat hair algae. I’ve heard from at least one hobbiest that sailfins eat more hair algae in his experience than other types of mollies.

In my opinion, though, dalmation mollies are the best looking.

Mystery Snails

Not a fish, but mystery snails are another good species to put in a tank with otos. They make a great clean up crew, and they won’t hurt any of the other fish in your aquarium.

Mystery Snail | (C) Tiny Underwater | License: CC-BY-4.0

I’ve got 4 in my aquarium, and they’re one of my favorite things in the aquarium.

They do fine if you occasionally feed them an algae wafer. If you have a messy enough aquarium – like mine – they can go for extended periods of time without needing food beyond what they can find in the aquarium.

Mystery snails also have 2 advantages above other snails like the nerite snail:

  1. They don’t try to escape your tank like nerite snails are notorious for doing.
  2. They don’t leave eggs that you have to scrape off everything in your aquarium.

They’re also kept by themselves in a lot of local fish stores, so I feel comfortable dropping them in without putting them through quarantine first.

Endlers Livebearers

Endlers Livebearers are a flashy, colorful fish that you can take care of without much difficulty.

They come in a bunch of different colors, and they like to dance and show off once they get comfortable in an aquarium.

They are a peaceful fish, so they’ll be perfectly happy in a tank with otos.

There is one downside to endlers, however:

Due to poor breeding practices, they seldom live past 2 years. (Even though their natural lifespan is 3-5 years.)

Because of this, you’ll want to find a trustworthy source to buy your endlers from, rather than just getting them from your local fish store. If you choose to buy online, Twin Cities Guppies is a reputable source. Otherwise, go for a trustworthy local breeder.

The good news is that – even though this can be more expensive – they’ll quickly breed and fill out your aquarium. A few breeding pairs will do you.

Endler guppy
Guppy endler, Poecilia wingei, freshwater aquarium fish, males in spawning coloration and female, courtship, biotope aquarium, closeup nature photo

A good stocking level for them is 1.5 per gallon of space that isn’t accounted for by other fish.

If you want to learn more about endlers, check out my care guide here.

Horseface Loaches

Another unusual choice for your aquarium is the horseface loach. These uncommon fish look absolutely bizarre and spend their days at the bottom of your aquarium burrowing into your substrate.

(Because of this, it’s best if you have sand.)

They do need at least a 55 gallon aquarium, and due to their sensitivity to water paremeters they’re best for aquarists with a bit of experience, but if you’re looking for an interesting fish that not everyone will have, this may be the one for you.

The horseface loach is an extremely peaceful fish, so they will definitely do well in a tank with otos. If you have any more aggressive fish, however, you may want to avoid these loaches, as they’ll end up getting bullied.

If you want to learn more about the horseface loach, read my guide here.

Lemon Tetras

Tetras are one of the most popular fish in the hobby, and they deserve their reputation.

They look great, are easy to take care of, and are small enough that you can keep a lot of them.

While not quite as colorful as other types of tetras such as neons or cardinals, lemon tetras are perhaps one of the hardiest of the tetras.

Due to bad breeding, a lot of the more common types are prone to a lot of genetic issues and random die off.

Most types of tetra still should be compatible with otos, however, including:

  • Neon Tetras
  • Cardinal Tetras
  • Black Skirt Tetras
  • Bleeding Heart Tetras

Since they are a schooling fish, you will need to keep a large group of them together – 15 or more. 20 is better. For this number combined with your group of otos, you’ll probably want at least a 29 gallon aquarium.