Otocinclus is one of the little algae eaters. They are peaceful and diligent, making them an excellent addition to planted aquariums.

They are easy to raise and care for, offer plenty of entertainment, and keep the algae under control.

For your Otocinclus to live and thrive normally, you need to comply with a few requirements for aquarium conditions and know “What to feed Otocinclus?

Keep reading for more information!

What to Feed Otocinclus?

Otocinclus are herbivores who primarily eat algae and biofilm (slime). They prefer to graze on green algae growing on decorations, substrate, plants, and aquarium glass.

Don’t confuse green spot algae and soft green algae. Green spot algae are extremely hard to remove, and Otocinclus does not consume them.

Many aquarists claim that the Otocinclus grazing Brown algae, or Diatom, often pop up in new tanks that have not matured.

The problem is that most tanks with a stable ecosystem cannot generate enough algae to sustain six Otos or more.

So it is necessary to add some extra food by feeding your Otocinclus with Catfish pellets or algae wafers.

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It is okay to supplement your fish diet with the following blanched vegetables:

  • Spinach
  • Romaine Lettuce
  • Brussel Sprouts
  • Zucchini (Courgette)

Thoroughly wash your vegetables to ensure they are free of pesticides before putting them into your fish tank.

When feeding your Otocinclus with blanched vegetables, you need to weigh them down so they will stay in one location long enough for your fish to reach it.

You can do it by attaching blanched vegetables to tiny rocks using a rubber band or using Veggie-Clips.

Avoid leaving your vegetables in your aquarium for more than three days.

Otocinclus eat algae

Otocinclus eat algae

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Brief Description of Otocinclus

Otocinclus are very small, usually 1.5 to 2 inches  (4 and 5 centimeters) in length. They have an elongated shape, are flattened ventrally, and are rounded on their back.

Otocinclus’ head is relatively flattened, with two eyes on either side, giving them lateral vision.

There is a suction cup in Otocinclus’ mouth, allowing them to feed and fixate on plants or rocks. This part is handy in the natural habitat.

Under proper care, you can expect your Otocinclus to live three to seven years.

Name Otocinclus Catfish
Scientific Name Otocinclus sp.
Other Names Otos, Dwarf suckers, Ottos, Oto cat, Dwarf Sucking Catfish, Midget Sucker Fish, and Dwarf Suckermouth.
Tank size (minimum) 10 gallons (about 40 liters)
Breeding Difficult
Keeping Medium
Optimal PH From 6.5 to 7.5
Optimal KH From 3 to 10
Optimal GH From 4 to 12
Optimal Temperature From 23 to 27 °C (From 73 to 80 °F)
Dwellers Mid and bottom
Diet Algae eater or herbivore
Nitrate Less than 20
Temperament Peaceful
Life span From 3 to 7 years
Color Form Black &white, olive-brown

Otocinclus in planted aquarium

There is a suction cup in Otocinclus’ mouth

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Otocinclus Aquarium Setup

Water Quality

  • Filter with a GPH rating 4x the volume of the tank.
  • No measurable nitrite or ammonia.
  • Nitrates should be between 0 and 20ppm.
  • Ideal pH: From 6 to 7.5.
  • Water Temperature: From 72 to 82°F (From 22 to 28°C).

Aquarium Size

Otocinclus are social species, often living in a large groups in the wild.

As a result, you should keep at least six individuals in the aquarium. A group of ten to fifteen individuals will be better.

A group of six Otocinclus will live well in a 20-gallon tank. However, you can also use a 10-gallon tank if you have no other choice.

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Tank Hardscape

Rounded stones and pre-soaked bogwood and branches will deliver Otocinclus with areas to graze.

Just be careful, and ensure avoiding any things with sharp surfaces. Your Otocinclus (and other aquatic species) may injure themselves and make an ideal environment for disease to establish.

Aquarium Plants

Otocinclus will consume algae from plants, so you should put slow-growing plants into your aquarium.

Fast-growing plants typically consume dissolved nutrients and carbon dioxide before algae have an opportunity to feed and grow.

Here are our guides for slow-growing plants that you can put in your aquarium:

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It is well worth the investment in the canister filter with a GPH rating of 4x the volume of the aquarium.

In addition, we recommend buying decent aeration and sufficient water circulation, so try adding water & air pump.

It is necessary to equip the appropriate LED lighting for live plants, test kits, and a CO2 injector to monitor the tank’s nitrite, nitrate, and ammonia levels.

The Behavior of the Otocinclus

Otocinclus is a social species found in large schools in the wild. They can often operate in schools with hundreds or even thousands of instances.

Otocinclus are often shy. Even if you keep them in a predator-free environment, your Otos don’t feel safe if you keep them in a small group.

For Otocinclus, small numbers are a certain sign of danger, so they will hide. Then, they don’t get enough food and eventually get stressed.

Otocinclus are also diurnal and prefer quickly swimming around your aquarium. When they feel intimidated during day time, they can become more active at night.

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How Many Species Does Otocinclus Include?

Otocinclus includes nineteen freshwater catfish species. Here are some of the most popular species in aquariums:

  • Otocinclus Vittatus.
  • Otocinclus Macrospilus.
  • Zebra Otocinclus (or Otocinclus Cocama)

What Algae Does Otocinclus Consume?

Otocinclus are great for controlling green dust algae, diatoms/brown algae, and green algae. They do not eat staghorn algae, or black, or red beard algae even when they’re starving.

Are Otocinclus Plants Safe in Planted Aquariums?

Yes, Otocinclus are absolutely safe in planted tanks.

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What Causes Huge Belly in Otocinclus?

Common causes are an internal parasite or a swim bladder problem.

Is Otocinclus Safe to Keep With Shrimp?

Otocinclus is the only fish in a community tank that is safe to live with shrimp.


What to feed Otocinclus? Otocinclus are herbivores and primarily consume slime (biofilm) and algae that builds up on plants and rocks.

You should keep slow-growing plants in your tanks to encourage algae growth and leaves for biofilm growth.

You also need to add catfish pellets or algae wafers to your Otocinclus diet.

We recommend adding some blanched vegetables to the fish tank, such as blanched zucchini, peas, spinach, and cucumber.

Thanks for reading!

Alex is a pet freelance writer and editor with more than 10 years of experience. He attended Colorado State University, where he earned a Bachelor’s degree in Biology, which was where he first got some experience in animal nutrition. After graduating from University, Alex began sharing his knowledge as a freelance writer specializing in pets.

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