Otocinclus Catfish: The Ultimate Care Guide
Otocinclus, also known as otos or dwarf suckermouth catfish, are peaceful and effective algae eaters that have become a favorite among aquascaping enthusiasts. In this guide, we explore their natural habitat, diet, behavior, breeding, and the best conditions for keeping them healthy and active in your aquarium.
Fun Facts About Otocinclus
Otocinclus belong to the Loricariidae family and include more than fifteen recognized species.
They remain small—usually between 2 and 5.5 centimeters in length—making them ideal for nano and planted aquariums.
Unlike many other catfish, they are active during the day and constantly graze on algae and biofilm.
Their peaceful temperament and hardworking nature make them perfect companions in community tanks.
In nature, they often form schools of dozens or even hundreds of individuals.
Natural Habitat
Otocinclus catfish originate from South America, where they inhabit the calm, shallow waters of the Amazon, Orinoco, and Paraná river systems.
They live among dense aquatic vegetation, roots, and driftwood, where oxygen levels are high and algae grow abundantly.
In their natural environment, Otocinclus spend most of their time attached to leaves, stones, and wood surfaces while grazing on soft green algae and microorganisms.
Diet and Feeding
Otocinclus are herbivorous fish that feed primarily on algae and plant-based foods.
In an aquarium, they thrive on a diet that includes:
Naturally growing soft algae and biofilm
Algae wafers and sinking plant-based pellets
Blanched vegetables such as zucchini, spinach, and cucumber
Foods containing spirulina and vegetable extracts
To maintain good health and bright coloration, it’s beneficial to supplement their diet with Green Bites, a soft, premium-quality food that provides essential vitamins and nutrients for small herbivorous and omnivorous fish.
It is essential to ensure there is always a food source available, as Otocinclus can easily starve in a clean or newly set-up aquarium. Remove any uneaten vegetables within a day to maintain good water quality.
Suitable Tank Mates
These catfish are completely peaceful and should be housed with other calm species.
Good companions include small schooling fish such as neon tetras, rasboras, guppies, and endlers, as well as bottom dwellers like Corydoras catfish.
They also coexist very well with shrimp species such as Amano and Cherry shrimp, and with peaceful snails like Nerite snails.
Avoid aggressive or territorial species such as cichlids, large barbs, or goldfish, as they can stress or injure the Otocinclus.
Ideal Aquarium Conditions
Temperature: 22–28 °C (72–82 °F)
pH: 6.0–7.5
Water hardness: Soft to moderately hard (up to 15 °dGH)
Minimum tank size: 60 liters for a small group
Substrate: Fine sand or smooth gravel
Decoration: Dense aquatic plants, driftwood, and smooth stones
A well-cycled, mature aquarium is essential before introducing Otocinclus. They are highly sensitive to fluctuations in ammonia and nitrite levels and should never be added to a newly established tank.
Social Behavior
Otocinclus are social fish that naturally live in groups. Keeping them in schools of at least six individuals helps reduce stress and encourages natural activity.
When kept alone, they may become shy, pale in color, and inactive. A group of Otocinclus is far more visible and lively, bringing both beauty and balance to a planted aquarium.
Breeding in Captivity
Breeding Otocinclus in home aquariums is possible but uncommon.
Successful spawning usually requires stable water conditions, a mature environment, and plenty of natural algae.
The female attaches small eggs to plant leaves, glass, or decorations, and the adults do not guard them.
If possible, the parents should be removed after spawning to prevent the eggs from being eaten.
The fry hatch within one to three days and feed on biofilm and powdered algae food.
Some species, such as the Zebra Oto (Otocinclus cocama), are particularly rare and require expert care.
Tips for Aquarists
Introduce Otocinclus only into established, stable aquariums that have been running for several months.
Provide constant access to algae or offer supplemental plant-based foods like Green Bites.
Perform regular partial water changes (25–30% weekly) to maintain high water quality.
Avoid rough decorations and strong water flow that could stress or injure the fish.
Observe behavior and appetite regularly—any sudden inactivity may indicate poor water conditions.
If you notice an outbreak of brown algae, which often appears in new aquariums, check our detailed guide on brown algae causes and removal methods for practical solutions.
Final Thoughts
Small, gentle, and endlessly helpful, Otocinclus catfish are among the most valuable additions to any planted aquarium.
Their continuous grazing keeps algae under control and helps maintain the natural beauty of the aquascape.
With proper care and stable conditions, these fascinating little catfish will thrive for years and contribute to a healthy, balanced ecosystem.
If you wish to learn more about compatible species and aquascaping tips, explore the other articles available in the Aquarium Boutique blog.
Frequently Asked Questions about Otocinclus Catfish
1. How many Otocinclus should be kept together?
Otocinclus are social fish that live in groups in the wild. It’s best to keep at least six individuals together to reduce stress and encourage natural schooling behavior.
2. Can Otocinclus live in a small tank?
They can live in smaller aquariums, but a minimum of 60 liters is recommended. A larger volume helps maintain stable water parameters and provides enough surfaces for algae growth.
3. How do I feed Otocinclus if there are no algae in the aquarium?
In very clean tanks, offer algae wafers, spirulina-based pellets, or soft plant-based food such as Green Bites to replace natural algae and biofilm.
4. Are Otocinclus suitable for planted aquariums?
Yes. They are one of the best choices for planted tanks because they gently clean leaves and hardscape surfaces without damaging plants.
5. Why did my Otocinclus die shortly after introduction?
These fish are sensitive to poor water quality and unstable conditions. They should only be introduced to mature, cycled aquariums. Gradual acclimation and steady parameters are essential for their survival.
6. Can Otocinclus be kept with shrimp?
Yes, they are completely shrimp-safe. In fact, both species help maintain a balanced ecosystem by consuming leftover food and algae.
7. How can I tell if my Otocinclus are healthy?
Healthy Otocinclus are active, feed constantly, and display a solid body shape with no sunken bellies. Lethargy, rapid breathing, or fading color may indicate stress or poor water quality.
8. How do I deal with brown algae in a new aquarium?
Brown algae (diatoms) are common in new setups. Otocinclus can help control them, but for a complete solution, read our detailed brown algae removal guide available on our blog.
9. Can Otocinclus breed in home aquariums?
Breeding is rare but possible in stable, mature aquariums with abundant algae. Females lay eggs on plants or glass, and fry feed on biofilm and fine powdered algae foods.
10. How long do Otocinclus live?
With proper care and diet, Otocinclus typically live between 3 and 5 years, sometimes longer in well-maintained planted tanks.
