Otocinclus Catfish Care: From Setup To Breeding

Otocinclus Catfish are really popular with fish keepers because they’re easy to care for and help to keep tanks clean by eating algae. But they need the right care to stay happy and healthy.

In this article, we’ll go over all the essentials of Otocinclus Catfish care, and more! So, keep reading to find out everything you need to know!


Otocinclus catfish are a fantastic option for those looking to add a diligent algae eater to their aquarium. These social fish thrive in groups of 4-6 or more. For housing, a tank that’s more horizontal and at least 10 gallons is ideal. The temperature should be kept between 73-81°F, and the pH should fall in the range of 6.0-7.5.

Being herbivorous by nature, their diet primarily consists of algae and plant matter, but supplementing with algae wafers will ensure they get all the nutrients they need.

Otocinclus catfish are generally hardy but can be sensitive to water changes and poor water quality. Monitoring the water parameters is essential to prevent potential issues like stress or diseases. With proper care, these little catfish can live for up to 5 years.

When considering tank mates, peaceful fish that won’t compete for food or disturb the Otocinclus are your best bet. Think about adding rasboras, smaller tetras, or other non-aggressive community fish to share their environment.

Are Otocinclus Catfish Easy To Keep?

Otocinclus catfish, most commonly known as Otos, are considered easy to keep for several reasons. First off, they’re quite hardy when it comes to water parameters. They can thrive in both soft and hard water, making them adaptable to various aquarium conditions.

However, these fish do particularly well in an established, well-planted tank. This is because they love eating algae and biofilm, which are often plentiful in such setups. So, they’re not just easy to keep, but also help keep your tank clean.

However, just like any pet, Otos need a bit of attention to stay healthy. You’ve got to keep their environment clean and stable. Big changes or dirty water can make them stressed or sick. So, regular water changes and watching the water conditions are key.

Another reason why Otos are easy to keep is that they’re peaceful. They get along with most other non-aggressive fish, making them a good choice for community tanks. Plus, they’re active and fun to watch.

(Here are 15 of the easiest fish to take care of! Voted for by over 150 fish keepers!)

NameOtocinclus Catfish (Macrotocinclus affinis)
Cost$2.49-$6.99+ Per Fish
OriginSouth America
Care LevelEasy
Lifespan5 Years
Size2 Inches
Tank Size10 Gallons
FeedingFish Flakes, Live Food, Blanched Vegetables
Community Tank Yes
Tank LevelMid Level
PlantsJava Moss, Anubias, Java Fern, Water Wisteria, Amazon Sword
Tank MatesNeon Tetras, Guppies, Cherry Shrimp, Corydoras Catfish, Dwarf Gourami, Rasboras, Mollies, Platies, Snails, Swordtails
Breeding TypeEgg Layer

Are Otocinclus Catfish Good For Beginners?

Otos are peaceful and great at cleaning algae, but they also need stable water conditions, which can be challenging for beginners. So if you’re planning on getting them, it might be helpful to have some experience keeping fish.


Otocinclus Catfish have a unique appearance that sets them apart. Their bodies are long and narrow, sort of like a pencil. You’ll also notice they have a flat belly, designed perfectly for sticking onto surfaces in the tank.

As for their color, it’s mostly grey or brown. But here’s the interesting part – they have a stripe running along their body. This stripe, usually a darker shade, starts from their mouth and goes all the way to the tail. It’s like a signature style for these fish!

Finally, let’s talk about their mouth. The Otos have a sucker-type mouth, which they use to cling onto surfaces and munch on algae. It’s pretty cool to watch them in action.


One thing about Otos is that they don’t grow very big at all. In fact, they typically max out at about 1-2 inches. Their petite size makes them ideal for smaller tanks and allows them to happily coexist with a range of other fish.


Otocinclus catfish are peaceful little fish. They love to swim around, mind their own business, and snack on algae. You might often find them clinging to the side of your tank, nibbling away at any algae they can find. But remember, while they’re generally friendly and calm, they like to hang out in groups.

So, remember, it’s always a good idea to have a few of them together in your tank.


On average, with proper care, an Otocinclus catfish can live for about 5 years. This can vary, though, depending on factors like the quality of care, diet, and tank conditions. To help ensure a long, happy life for your Otos, you’ll want to keep their tank clean, provide a diet rich in algae, and maintain suitable water conditions.

Water Parameters

Let’s discuss the specific water parameters that are ideal for your Otocinclus Catfish to ensure their happiness in your tank.

NameOtocinclus Catfish
Tank Size10 Gallons


First off, let’s look at pH. Generally, Otocinclus Catfish like their water slightly acidic to neutral. This means a pH of around 6.0 to 7.5 is just right for them. A stable pH within this range helps keep your Otos happy and healthy.


Otocinclus Catfish thrive in warmer waters, and the ideal temperature for them is between 73 and 81°F. To keep your Otos comfortable, you’ll need a heater in your tank to maintain a steady warm temperature.

Water Hardness

For Otocinclus Catfish, a water hardness of 1 to 2 dGH works best. This means the water should be slightly hard to hard. And, of course, maintaining a stable level within this range is crucial for your Otos’ well-being.

Tank Size

Given their small size, you might think Otocinclus Catfish could make do with a tiny tank. But remember, they love company, so you should have a group of them. For this reason, a tank of 10 gallons or larger is best for your Otos. This gives them enough room to swim around, stick together, and do their thing.

Otocinclus Catfish Care Sheet

If you want to know about the most colorful fish for your aquarium, you’re going to LOVE this article!

What Do Otocinclus Catfish Like In The Wild?

Otocinclus catfish are small, peaceful fish that love to hang out in freshwater streams and rivers in Central and South America. They can be found in a variety of habitats, from clear, slow-moving waters with sandy or muddy bottoms to warm and humid areas with water temperatures ranging from 72 to 78°F.

The plants and animals that live in Otocinclus catfish’s natural habitat are diverse. Some of the plants that can be found in their habitat include Amazon sword plants, water lettuce, and hornwort. These plants provide food and shelter for your catfish, giving them a safe place to hide.

Otos also like being around other Otos. In the wild, they hang out in large groups, looking for food together and hiding from dangers. So, if you have Otos in a fish tank, it’s best to have a group of them.

If you’re thinking about keeping Otocinclus catfish in an aquarium, it’s important to recreate their natural habitat as closely as possible.

How To Setup A Tank For Otocinclus Catfish 

Setting up a tank for otocinclus catfish is relatively simple. However, there are a few key things to keep in mind to create a healthy and comfortable environment for these amazing fish.

Choose the Right Tank Size

Otocinclus catfish are small fish, so you don’t need a very large tank. A 10-gallon tank is a good size for a small group of Otocinclus catfish.

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Add a Heater 

Otocinclus catfish prefer water temperatures between 73 and 81°F. To keep the water within this temperature range, you’ll need a heater. First, choose a heater that’s the right size for your tank. Once you have chosen a heater, install it according to the manufacturer’s instructions. 

Tetra HT Submersible Aquarium Heater With Electronic Thermostat, 50-Watt, 2-10 Gallon
  • All Tetra HT heaters have indicator lights to let you know when the heater is on. It will be red when heating and green when the proper temperature has been reached..All Tetra HT Heaters will shut off if an electrical short is detected for your safety.

Add a Filter

Otocinclus catfish also need a filter to help keep the water in their tank clean. The filter will remove waste products and debris from the water, which will help to keep the water quality high. Consider the size of your tank and the amount of filtration that’s needed

Aqueon QuietFlow 10 LED PRO Aquarium Fish Tank Power Filter For Up to 20 Gallon Aquariums
  • LED indicator light flashes when water cannot pass through the cartridge, generally indicating it’s time to change the cartridge

Add a Substrate

Otocinclus catfish prefer a sandy or muddy substrate. You can use commercial aquarium sand or a natural substrate like aquarium soil.

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Add Plants

Otocinclus catfish like to have plenty of hiding places, so you should add some plants to your tank. You can use live plants or artificial plants. Live plants will help to keep the water quality in the tank healthy.

Condition the Water

Before you add your Otocinclus catfish to the tank, you will need to condition the water. This means adding a water conditioner to the water to remove chlorine and chloramine. You can also add a water dechlorinator as an option.

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Test the Water

Once you have conditioned the water, you need to test the water quality. You should test the pH, ammonia, nitrite, and nitrate levels. The pH should be between 6.0 and 7.5. The ammonia and nitrite levels should be zero. The nitrate level should be below 20 ppm.

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Adding Your Otocinclus Catfish

When introducing Otocinclus catfish to an aquarium, it’s important to gradually acclimate them to the water temperature. Start by floating the bag containing the fish in the aquarium for 15-20 minutes, then slowly introduce small amounts of aquarium water into the bag over the course of several repetitions. 

Once the water in the bag is mostly from the aquarium, you can let your Otos float for another 15-20 minutes before releasing them into the tank. Keep an eye on them for the first few hours to ensure they’re adjusting well and behaving normally.

(If you’re setting up a fish tank for the first time, check out this article on how to do so and how to avoid the most common 24 beginner mistakes!)

Otocinclus Catfish Male Vs Female

Otos are pretty tiny fish, and it can be hard to tell males and females apart because they look similar. But if you’re patient and have a keen eye, you might notice a few differences.

First, let’s talk about size. Generally, female Otos are a bit bigger than males. They have rounder, fuller bodies, especially when they’re ready to lay eggs. So if you see an Oto that’s got a bit of a belly on her, it’s probably a lady Oto.

Male Otos, on the other hand, are usually smaller and more streamlined. They don’t have rounded bellies like the females. But remember, this isn’t always a surefire way to tell. Some Otos just like their algae a bit too much and might have a bigger belly regardless of their gender!

The color of the females can also be brighter than the males. Some people also say that males might have a special flap of skin on their back, but this is not always the case. It’s important to know that these signs might not be true for all Otocinclus catfish.

Otocinclus Catfish Diet

Otos are famous for being algae eaters. In fact, that’s their main job in your tank – to help keep it clean by eating up the algae. If your tank’s got a lot of algae, then it’s like an all-you-can-eat buffet for these little fish.

But sometimes, especially in a super clean tank, there might not be enough algae. If that’s the case, you can give them a bit of a helping hand. Your Otos will also happily eat veggies like zucchini or cucumber. Just make sure to blanch them first; it makes it easier for the Otos to eat.

And don’t forget about algae wafers! These can be a great supplement to their diet, especially in a tank that doesn’t have a lot of natural algae. Just toss one in and watch your Otos as they happily munch on it.

But remember, just like us, Otos enjoy variety in their diet. So, don’t be afraid to switch things up now and then.

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Do Otocinclus Catfish Need Algae?

Otos love algae because it makes up a huge part of their diet. If there aren’t enough algae in your tank, supplement their diet with algae wafers or blanched veggies.

Will Otos Eat Dead Plants?

Dead plant matter isn’t your Otos first choice, but they might nibble on it if they’re really hungry. But generally, Otos prefer to munch on algae. 

What Is The Best Way To Feed An Otocinclus Catfish?

You can feed your Otos with algae wafers if there’s not enough natural algae in your tank. They also love blanched veggies like zucchini, spinach, and peas. Just make sure to remove uneaten food after a day to keep the water clean.

Otocinclus Catfish Tank Mates 

Now let’s go over which tankmates your Otocinclus Catfish enjoy having in their tank and why they’re great choices.

Neon Tetras

These guys are peaceful and mind their own business, just like the Otos. They’re small, colorful, and won’t bother your Otos one bit.

Neon Tetra Care Sheet


Guppies are also peaceful fish that won’t try to pick on your Otos. Plus, guppies and Otos both love a well-planted tank.

Guppy Care Sheet

Cherry Shrimp

Otos and Cherry Shrimp can be great pals because they both enjoy snacking on algae and won’t fight over space.

Cherry Shrimp Care Sheet

Corydoras Catfish

These are another kind of catfish that are really peaceful. They hang out at the bottom, while Otos are more likely to stick to the sides and plants, so they get along fine.

Common Corydoras Care Sheet

Dwarf Gourami

Dwarf Gouramis are calm, making them an ideal tankmate for Otos. They also thrive in similar water conditions.

Dwarf Gourami Care Sheet


Rasboras are non-aggressive fish, and their fast-moving nature shouldn’t stress out the laid-back Otos.

Harlequin Rasbora Care Sheet


Mollies are known to be good-natured fish that coexist nicely with Otos. They share a similar diet too, which can make feeding time more convenient.

Molly Fish Care Sheet


Platies are friendly, sociable fish that get along with just about everyone, including Otos. They thrive in similar water parameters as well.

Platy care sheet


Be it Nerite Snails, Mystery Snails, or any other peaceful snail species, they can cohabit well with Otos. They both enjoy algae, and the Otos won’t bother them.

Nerite Snails Care Sheet


Swordtails are not aggressive, and they’re hardy fish that can tolerate a wide range of water conditions, making them a good choice for beginners. 

Swordtails Care Sheet

(If you want to know about some of the best community fish, then check out this article!)

Otociclus Catfish Tank Mates

Otocinclus Catfish Plants

Let’s explore some of the best plants for your Otocinclus Catfish to ensure their happiness.

Java Moss

First up is Java Moss. It’s a perfect plant for Otos because it grows easily and creates a comfy carpet for them to lounge on. Plus, it can help maintain the water quality in the tank.

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Next is Anubias. These hardy plants have broad leaves where algae love to grow, giving your Otos a snack bar right at home! And don’t worry, these plants don’t mind a little munching.

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Java Fern

Java Ferns are another great option. They’re hardy and easy to care for, just like Anubias, and their leaves are an excellent place for algae to grow.

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Water Wisteria

Water Wisteria not only gives your Otos plenty of hiding places but also helps control the nutrients in the water, reducing excess algae.

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Amazon Sword

Lastly, the Amazon Sword. This plant is sturdy and can withstand the Otos’ constant scouring for food. Its large leaves also provide excellent cover.

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Otocinclus Catfish Breeding

Breeding Otos isn’t the easiest thing about caring for them. It can be a little tricky, but with patience and care, you can get them to spawn.

First, you need to tell the males from the females. Males are usually smaller and slimmer, while females are larger and rounder, especially when they’re full of eggs.

Next up, food! A varied diet can help stimulate breeding. So, in addition to their regular algae meals, offer them treats like blanched veggies and high-quality sinking pellets. And remember, their breeding can be stimulated by high-protein diets, which may include daphnia, algae wafers, and brine shrimp.

To properly set up a breeding tank for otos, it’s crucial to mimic their natural habitat. Start by checking that the water conditions match those mentioned above. Then, add plenty of plants and decorations to create hiding places for them. Finally, make sure to have a gentle water flow, similar to their river habitat.

When they breed, they behave similarly to Corydoras species. The female will rush around the tank pursued by the male, eventually catching up and coupling in a T-shaped position. Then, the female oto will lay her eggs on flat surfaces such as plants or the sides of the tank.

Once you see eggs (tiny, clear dots) attached to the glass or plants, you’re in business! The eggs will hatch in about 2-3 days, and the fry will start feeding on algae almost immediately.

Remember, baby Otos are tiny and can be a tasty treat for other fish. So, it’s best to raise them in a separate tank where they can safely grow.

Otocinclus Catfish Common Diseases 

Here are some of the most common Otocinclus Catfish diseases and what actions you can take to treat them.

DiseaseSymptoms or CausesSuggested Action or Treatment
IchWhite spots on body and fins, flashing behaviorTreat with medication containing formalin or malachite green
Velvet DiseaseYellow or grayish film on body, loss of appetiteTreat with copper-based medication
Mouth FungusWhite or gray patches on mouth or lipsImprove water quality, treat with antifungal medication
ColumnarisCotton-like growth on body or fins, ulcers or soresImprove water quality, treat with antibiotics or antifungals
Parasitic InfectionsScratching or rubbing against objects, visible parasitesTreat with appropriate medication for specific parasite

How Many Otocinclus Catfish Can You Keep Together?

When keeping Otocinclus catfish in an aquarium, it’s recommended that you house at least 6 together. They feel safer and more comfortable in this setting.

However, if your tank size is limiting, a 10-gallon tank can comfortably house 4-6 Otocinclus. If you have the capacity for a larger tank, the ideal number of Otocinclus catfish to keep together is between 15-20.

Please remember that keeping less than 6 Otocinclus catfish can lead to them becoming more shy and, overall, not a good idea.

Facts About Otocinclus Catfish

Your Otocinclus Catfish are pretty interesting fish, and here are a few interesting facts about them that’ll make you love them even more!

  1. Otos are great friends to have in your aquarium! They love to munch on algae, helping to keep your tank clean.
  1. Their name is a bit of a tongue twister! “Otocinclus” comes from the Greek words “oto”, meaning ear, and “klinein”, meaning bed – a reference to the suction-cup-like mouth they use to attach to surfaces.
  1. They come from South America. Otos are found in slow-moving or still waters in countries like Brazil, Argentina, and Colombia.
  1. Otos prefer the lights off. Otos are more active during dawn, dusk, and night, which makes sense because algae growth is usually higher in the dark.
  1. Breeding them in captivity is a tough job. While not impossible, it requires a very specific set of conditions to get them to spawn.

What Are The Different Types Of Otocinclus Catfish?

Here’s a little more about the most common types of Otocinclus Catfish:

  • Common Oto: One of the most popular types of Otos, Common Otos are found in South America, even in parts of the Amazon River. They’re speckled brown on top, white underneath, with a neat brown stripe from head to tail.
  • Zebra Oto: True to their name, Zebra Otos have bold black and white stripes. These stripes aren’t straight, giving them the alternate name Tiger Otos.
  • Dwarf Oto: Dwarf Otos look similar to the Common Oto, but their tail fin is a bit different. The signature brown stripe fades out by the tail, and there’s a blotch on it too.
  • Golden Oto: Often mistaken for Common Otos, they’re recognized by their less obvious brown stripes that can look golden.
  • Silver Oto: Much like its name suggests, the Silver Oto’s brown patterns look more silver. Other than that, it’s hard to tell this one apart from its Oto cousins.


Why Is Your Otociclus Catfish Swimming Upside Down?

If you see your Otocinclus Catfish swimming upside down, it could be a sign of swim bladder disorder or poor water quality. Make sure to check your water parameters and consult a vet if needed. 

Do Otocinclus Go Up For Air?

Otocinclus catfish aren’t known for gulping air like some other fish species. If you notice this behavior, it might be a sign of low oxygen levels in your tank.

Do Otocinclus Need Driftwood?

While not a strict requirement, driftwood is beneficial for your Otocinclus Catfish’s tank. Otos love to graze on the biofilm that grows on it, and it also helps to mimic their natural habitat.

Do Otocinclus Eat White Mold?

Otos primarily eat algae and aren’t known to eat mold. If you’re seeing white mold in your tank, it’s a sign of decaying organic matter that should be cleaned up.

Is 3 Otocinclus Catfish Enough?

As mentioned in this article, it’s recommended that you keep at least 4-6 Otos together. They feel safer and more comfortable in this setting. Although some decide to keep fewer Otos together, the ideal number should be 6 or more.


Otocinclus catfish are a great addition to any aquarium. They’re easy to care for, peaceful, and helpful in keeping tanks clean. If you’re looking for a small, low-maintenance fish, otocinclus catfish are a great choice. By following the care tips in this article, you can ensure that your Otos will thrive!

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