Otocinclus Quick Care Guide

by Kevin

Otocinclus on a piece of wood in a planted aquarium.

Otocinclus, commonly known as “Otos,” Oto cats” or “dwarf suckers,” are small, peaceful fish belonging to the Loricariidae family. They are known for their algae-eating abilities, making them excellent companions for a variety of freshwater community tanks.

Originally from South America, Otocinclus typically reach 1-2 inches (2.5-5 cm) in length. Despite their hardworking nature, they can be delicate and require specific care to thrive.

Closeup of an Otocinclus resting on an leaf in a planted aquarium.

Properly caring for Otocinclus involves understanding their natural habitat, behavior, and dietary needs.

The goal of this guide is to provide you with a quick overview of what it takes to care for Otocinclus. If you decide that Otocinclus are the right fish for you, I highly recommend doing some additional research on YouTube to see how other aquarists care for and keep these fish.

1. Tank Size

A minimum of 10 gallons (38 liters) for a small group is adequate, a 20-gallon is ideal. Otocinclus are social creatures and do best in groups of at least 5-6, as this helps reduce stress and encourages natural behavior.

2. Water Conditions

Temperature: Maintain water temperatures between 72°F and 79°F (22°C to 26°C).

pH: Aim for a pH level between 6.5 and 7.5.

Water Hardness: Keep the water hardness between 6-15 dGH.

Filtration: Use a sponge filter or one with adjustable flow, as Otocinclus prefer gentle water movement. Make sure the intake is covered to prevent small fish from getting sucked in.

Aeration: Adequate oxygenation is important for these fish. Ensure your tank has good surface movement without creating strong currents.

3. Diet and Feeding

Otocinclus eating algae on glass.

Otocinclus primarily feed on algae in the wild but often the aquarium does not provide enough algae to sustain them.

Supplement their diet with:

1) Algae wafers or tablets.

2) Blanched vegetables (zucchini, cucumber, and spinach).

Ensure food pieces are small enough for them to eat.

Feed your Otocinclus once a day in the evening, mimicking their natural feeding time. Remove uneaten food to prevent water quality issues.

4. Tank Mates

Choose peaceful, small to medium-sized fish as tank mates. Avoid aggressive fish that may stress or harm them. Good companions include small tetras, rasboras, and dwarf corydoras.

5. Health and Maintenance

Water Changes:

Perform weekly water changes of 20-40% to maintain water quality. Otocinclus are sensitive to ammonia, nitrites, and high nitrate levels.


Regularly check for signs of stress or illness, such as lethargy, loss of appetite, or unusual swimming patterns.

Quarantine New Fish:

Always quarantine new arrivals for at least 2-4 weeks to prevent the spread of diseases to your established community.

6. Common Issues and Solutions


Otocinclus can be prone to common freshwater ailments like Ich or fungal infections. Early detection and treatment are crucial.


Ensure they have a constant source of food. Algae growth might not be sufficient, so supplementing their diet is necessary.


Take care when introducing Otocinclus to a new tank. Acclimate them slowly over several hours to reduce stress and shock.

7. Advanced Care Tips

Algae Availability:

While supplemental feeding is important, providing a natural source of algae can help Otocinclus thrive. This can be done by taking algae from another tank or leaving tank light on for longer to encourage algae growth.


Proper lighting supports plant and algae growth, which in turn benefits your Otocinclus. A moderate lighting setup, with a daily cycle of 8-10 hours, can promote a healthy amount of algae. Be careful to avoid excessive light, as it can lead to uncontrolled algae blooms and potential water quality issues.


A soft, sandy substrate is ideal for Otocinclus. While they spend most of their time attached to the tank’s glass and decorations, a gentle substrate can help prevent injuries when they do explore the bottom. Additionally, it supports the growth of beneficial bacteria and microorganisms that can contribute to the tank’s ecosystem and provide additional food sources.

8. Troubleshooting Common Problems

Aggression from Tank Mates:

Otocinclus are peaceful and can easily become targets for nippier or more aggressive fish. Monitor their interactions closely, especially during feeding times, to ensure they are not being outcompeted for food or harassed. If problems persist, you may need to reconsider the tank’s community composition.

Signs of Stress:

Otocinclus showing signs of stress, such as hiding excessively, erratic swimming, or losing their grip on surfaces, may indicate water quality issues or illness. Regularly test the water parameters and look for signs of disease. Stress can also be a symptom of poor diet, so make sure your Oto is receiving a varied and consistent diet.

Breeding Otocinclus:

Breeding Otocinclus in captivity can be challenging but rewarding. A significant change in water parameters, mimicking the onset of the rainy season in their natural habitat, can trigger spawning. This often involves a large water change with slightly cooler water and increased feeding. However, breeding success varies greatly, and raising the fry requires a supply of microscopic food to match their tiny mouths.


Caring for Otocinclus catfish can be a deeply rewarding experience, offering both a natural solution to algae control and a fascinating glimpse into the behavior of these gentle fish. By creating a stable, well-maintained environment and paying close attention to their needs and behaviors, aquarists can enjoy the company of these small, industrious creatures for many years.

I hope you learned something new about Otocinclus. Check out my article on the best algae eaters if you want to discover other fascinating fish and invertebrates that help keep aquariums clean.

Or, if you are planning on setting up a new aquarium, take a look at my article on the best fish for 10 gallon aquariums.

As always, stay zen.