Last update: November 2, 2023

What Do Otocinclus Eat? The Ultimate Guide to Diet, Care & Behaviour

Otocinclus, also known as dwarf suckers or otos, are a small species of catfish that are popular among aquarium enthusiasts.

These fish are known for their ability to help keep tanks clean by eating algae and other debris. However, many people wonder what exactly otocinclus eat to stay healthy and thrive in a home aquarium.

Understanding Otocinclus is key to providing them with the proper care and diet they need. These fish are native to South America, where they live in rivers and streams with fast-moving water.

In the wild, otocinclus feed on a variety of algae, including diatoms, green algae, and blue-green algae. They also eat small invertebrates like insect larvae and crustaceans.

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To ensure that otocinclus stay healthy and happy in a home aquarium, it’s important to replicate their natural habitat as closely as possible.

Feeding and Diet are crucial components of otocinclus care. In a home aquarium, otocinclus should be fed a varied diet that includes algae wafers, blanched vegetables, and live or frozen foods like brine shrimp or daphnia.

It’s important to avoid overfeeding otocinclus, as they have small stomachs and can easily become bloated. Additionally, it’s important to make sure that any food given to otocinclus sinks to the bottom of the tank, as these fish are primarily bottom-dwellers.

Key Takeaways on What Do Otocinclus Eat

  • Otocinclus are a species of catfish that eat algae, small invertebrates, and other debris in the wild.
  • In a home aquarium, otocinclus should be fed a varied diet that includes algae wafers, blanched vegetables, and live or frozen foods.
  • It’s important to replicate otocinclus’ natural habitat as closely as possible and avoid overfeeding them to ensure their health and happiness.

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Understanding Otocinclus

Otocinclus, also known as otocinclus catfish or dwarf suckers, are part of the Loricariidae family. They are small fish that are commonly found in freshwater aquariums.

The appearance of otocinclus is characterized by their slender body, round head, and sucker-like mouth that they use to cling onto surfaces.

In terms of behavior, otocinclus are active and diurnal fish that prefer to swim in schools. They are generally peaceful and have a friendly temperament towards other fish in the aquarium.

The common oto and the golden oto are two of the most popular species of otocinclus. The common oto, also known as Otocinclus vittatus, is a small fish that grows up to 2 inches in length.

The golden oto, also known as Otocinclus cocama, has a similar size but has a golden-yellow coloration.

Another species of otocinclus is the Otocinclus macrospilus, which is slightly larger than the common oto and has a distinctive black and white spotted pattern on its body.

When it comes to their diet, otocinclus are known to be herbivores. They primarily feed on algae and other plant matter that grows on surfaces in the aquarium.

It is important to provide them with a varied diet that includes algae wafers, blanched vegetables, and other plant-based foods.

Natural Habitat

Otocinclus are naturally found in South America, specifically in the Amazon River basin and its tributaries.

They are commonly found in rivers and streams with slow-moving water and sandy or muddy bottoms. Otocinclus are also found in shallow ponds and flooded areas during the rainy season.

In their natural habitat, Otocinclus feed on algae that grow on rocks, plants, and other surfaces in the water. They are known to be herbivores, and their diet consists mainly of algae, diatoms, and other microorganisms.

Also, Otocinclus adapt their diet according to the season in their natural habitat. During the rainy season, they are known to consume more protein-rich foods like insect larvae, while in the dry season, their diet leans heavily on algae and plant matter. Mimicking these seasonal diet changes in the aquarium setting can add to the well-being and longevity of the fish.

Otocinclus are also known to feed on small invertebrates, such as insect larvae and crustaceans.

In Venezuela, Otocinclus are commonly found in the Orinoco River basin, while in Argentina, they are found in the Paraná River basin. Otocinclus are also found in other countries in South America, including Brazil, Colombia, and Peru.

Aquarium Setup

When it comes to setting up an aquarium for Otocinclus, there are a few key factors to consider. The following paragraphs will cover the necessary information to ensure a healthy and thriving environment for your Otocinclus.

Tank Size and Water Parameters

Otocinclus are small fish and do not require a large tank. However, it is recommended to have at least a 10-gallon tank for a small group of Otocinclus.

It is important to maintain a stable water environment for these fish. The recommended water parameters are pH between 6.5-7.5, GH between 3-10, and temperature between 72-78°F. It is important to monitor these parameters regularly and make adjustments as needed.

Otocinclus are sensitive to changes in water conditions. When you bring them home for the first time, it’s crucial to acclimatize them properly to avoid stress or shock. A gradual acclimatization process that involves slowly mixing tank water with the water from the pet store can help in successful transplantation.

Substrate and Decorations

Otocinclus prefer a soft substrate such as sand or fine gravel. It is important to avoid sharp or rough substrates that can damage their delicate barbels.

Adding live plants to the aquarium can also provide hiding spots and a natural environment for the fish. Decorations such as driftwood and rocks can also be added, but make sure they do not have sharp edges that can harm the fish.

Filtration and Water Changes

A good filtration system is essential for maintaining good water quality in the aquarium. It is recommended to have a filter that can process at least 5-10 times the volume of the tank per hour.

Regular water changes of 25% every two weeks can also help maintain good water quality.

Feeding and Diet

Otocinclus are herbivores and primarily feed on algae and plant matter. In their natural habitat, they graze on algae growth and soft green algae found on rocks and other surfaces in the water.

In captivity, otocinclus can be fed a variety of foods to ensure they receive proper nutrition. Algae wafers, blanched vegetables such as zucchini, cucumber, and spinach, as well as lettuce are all good options. Pellets specifically designed for algae eaters can also be given.

Otocinclus fish can engage in a fascinating form of symbiosis with certain species of aquarium plants. Some aquatic plants benefit from the Otocinclus’ voracious appetite for algae, which helps keep the plants’ leaves free from algae buildup, enhancing their photosynthesis process. In return, the Otocinclus enjoy a healthy and ongoing supply of their favorite meal.

Algae and plant matter may provide Otocinclus with most of their nutritional needs, but what about their overall shell and bone health? Some aquarists recommend adding calcium supplements to ensure that your Otocinclus maintain a robust physical structure. This is especially crucial in softer water conditions where calcium and other minerals may be lacking.

It is important to note that otocinclus should not be overfed, as they have a small digestive system and can easily become bloated. It is recommended to feed them small portions multiple times a day instead of one large feeding.

To supplement their diet, some owners also offer Repashy, a gel food that contains a mix of plant-based ingredients. This can be a good option for otocinclus that may not be getting enough nutrition from their regular diet.

Tank Mates

Otocinclus are peaceful fish that get along well with other peaceful fish, invertebrates, and snails. They are a social species that prefer to live in groups, so it is best to keep them with other schooling fish.

When it comes to tank mates, it is important to choose species that have similar water requirements. Otocinclus prefer soft, slightly acidic water, so it is best to avoid fish that require hard, alkaline water.

Some suitable tank mates for otocinclus include:

  • Corydoras: These peaceful bottom-dwellers are great companions for otocinclus. They have similar water requirements and are both social species that prefer to live in groups.
  • Tetras: Small, peaceful tetras like neon tetras and ember tetras make great tank mates for otocinclus. They are both schooling fish that prefer to live in groups, and they have similar water requirements.
  • Shrimp: Many species of shrimp, including cherry shrimp and ghost shrimp, can coexist peacefully with otocinclus. They are both peaceful, non-aggressive species that prefer to live in groups.
  • Snails: Snails like nerite snails and mystery snails make great tank mates for otocinclus. They are both peaceful species that help keep the tank clean by eating algae and other debris.
  • Pleco: Some species of pleco, such as the bristlenose pleco, can coexist peacefully with otocinclus. However, it is important to choose a species that has similar water requirements and won’t outgrow the tank.

Health and Care

Otocinclus are generally hardy fish that can adapt well to various water conditions. However, proper care is essential to ensure their health and longevity in the aquarium. Here are some tips on how to care for otocinclus:

1. Water Quality and Maintenance

Maintaining good water quality is crucial for the health of otocinclus. Regular water changes are necessary to remove accumulated waste and keep the water parameters stable.

Otocinclus are sensitive to high levels of ammonia and nitrite, so it’s essential to keep these levels as close to zero as possible.

2. Diet

Otocinclus are primarily herbivorous and feed on diatoms, biofilm, and algae in the wild. In the aquarium, they should be offered a varied diet that includes algae wafers, blanched vegetables, and spirulina-based foods.

It’s important to avoid overfeeding otocinclus, as they can easily become overweight and prone to health issues.

3. Cleaning

Regular cleaning of the aquarium is necessary to prevent the buildup of harmful bacteria and other pathogens.

The substrate should be vacuumed during water changes to remove uneaten food and other debris. It’s also important to clean the filter regularly to ensure it’s functioning correctly.

4. Stress

Otocinclus can become stressed in certain situations, such as sudden changes in water parameters or the presence of aggressive tank mates. It’s important to provide them with a peaceful environment and avoid overcrowding the aquarium.

5. Size

Otocinclus are small fish and only grow to be around 2 inches in length. As such, they are best kept in small groups in a tank that is at least 10 gallons in size.


Breeding Otocinclus can be a challenging task, but it is possible with proper care and attention. Here are some tips to help you get started:

  • Before breeding, make sure you have a healthy and mature pair of Otocinclus. They should be at least a year old and in good condition.
  • Create a separate breeding tank with the appropriate water conditions. The water should be soft, slightly acidic, and have a temperature between 72-78°F.
  • Provide hiding places such as plants, caves, or PVC pipes for the Otocinclus to lay their eggs.
  • Feed them a varied diet of algae, vegetables, and high-quality fish food to ensure they are getting the necessary nutrients.
  • Once the female is ready to lay eggs, she will lay them on the chosen surface and the male will fertilize them.
  • After fertilization, remove the adults from the breeding tank to prevent them from eating the eggs.
  • The eggs will hatch in 3-5 days, and the fry will begin to swim freely after 3-4 days.
  • Feed the fry small amounts of infusoria or commercial fry food several times a day until they are large enough to eat the same food as the adults.

Breeding Otocinclus can be a rewarding experience for dedicated hobbyists. With proper care and attention, you can successfully breed and raise healthy Otocinclus fry.

Buying Guide

When it comes to buying food for otocinclus, there are a few things to keep in mind to ensure that you are getting the best product for your fish. Here are some tips to help you choose the right food:

1. Look for High-Quality Ingredients

When it comes to choosing food for otocinclus, look for products that contain high-quality ingredients.

This means looking for foods that are made from whole, natural ingredients and that do not contain any artificial colors, flavors, or preservatives. Foods that are made from natural ingredients are typically more nutritious and easier for fish to digest.

2. Consider the Nutritional Value

When choosing food for otocinclus, it’s important to consider the nutritional value of the food. Look for foods that are high in protein and low in fat, as this is the ideal diet for otocinclus.

Additionally, look for foods that contain vitamins and minerals that are essential for fish health.

3. Check the Expiration Date

Before purchasing any food for otocinclus, check the expiration date to ensure that the food is fresh and has not expired. Expired food can be harmful to fish and may contain harmful bacteria that can make them sick.

4. Consider Your Aquarium Setup

When choosing food for otocinclus, consider your aquarium setup. If you have a planted aquarium, for example, you may want to choose a food that is designed to be gentle on slow-growing plants.

Additionally, if you have other low-maintenance fish in your aquarium, you may want to choose a food that is appropriate for all of the fish in your tank.

5. Shop at a Reputable Pet Store

When purchasing food for otocinclus, it’s important to shop at a reputable pet store. This will ensure that you are getting high-quality products that are safe for your fish.

Additionally, pet stores often have knowledgeable staff who can help you choose the best food for your fish and answer any questions you may have.

Frequently Asked Questions

What are some suitable foods for Otocinclus catfish?

Otocinclus catfish are primarily herbivorous and require a diet that is high in vegetable matter. Some suitable foods for Otocinclus catfish include algae wafers, spirulina flakes, and blanched vegetables such as zucchini, cucumber, and spinach.

Can Otocinclus catfish survive on just algae?

While Otocinclus catfish primarily feed on algae in the wild, it is not recommended to rely solely on algae in a home aquarium. A varied diet that includes other types of food is important for their overall health and well-being.

What other types of food should I offer my Otocinclus catfish?

In addition to algae and vegetable matter, Otocinclus catfish can also be fed small amounts of high-quality protein such as brine shrimp, bloodworms, and daphnia. It is important to not overfeed them with protein-rich foods as it can lead to health issues.

How often should I feed my Otocinclus catfish?

Otocinclus catfish should be fed small amounts of food multiple times a day. A good rule of thumb is to feed them 2-3 times a day with only as much food as they can consume in a few minutes. Overfeeding can lead to health issues and poor water quality.

What are some recommended tank mates for Otocinclus catfish?

Otocinclus catfish are peaceful and can be kept with a variety of other fish species that are also peaceful and do not have aggressive tendencies. Some suitable tank mates include tetras, guppies, and rasboras.

How many Otocinclus catfish can be kept in a 20 gallon tank?

A 20 gallon tank can comfortably house 4-6 Otocinclus catfish. It is important to not overcrowd the tank as it can lead to poor water quality and stress for the fish.

Do Otocinclus eat diatoms?

Yes, Otocinclus are well-known for their ability to eat diatoms in the aquarium. These algae-eating fish are excellent at keeping your tank clean by consuming diatoms that may otherwise grow on plants, rocks, and glass surfaces. Diatoms are a part of their natural diet in their habitats, so they’re well-suited for this task.

Ian Sterling

Ian Sterling, founder of, began his aquarium journey over 30 years ago, driven by a deep fascination for fish and their diverse personalities. His website,, is dedicated to making fishkeeping accessible and enjoyable, offering beginner-friendly guidance, expert insights, and a community for aquarists to connect and share experiences.

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