Otocinclus Catfish Care Tips

Otocinclus catfish are a type of fish that can be found in freshwater environments. They have many characteristics that make them unique and interesting, such as their otoliths (ear stones) and the ability to produce light by bioluminescence.

They are freshwater fish found in South America and Mexico. They live in the moving water of streams, rivers, and lakes. Otocinclus catfish get their name from their round body shape and otoliths that look like ears on each side of their head.

These otoliths help them to hear prey better than other fish species because they can pick up vibrations from all directions. One way this helps otocinclus catfish is by detecting the sound of larger predators nearby so it can swim away before being eaten!

Origin and description

Otocinclus catfish


The otocinclus catfish is a small freshwater fish that originates from South America. They typically grow to be about two inches long and are often used as algae eaters in aquariums. They have a black body with silver markings and are popular for their peaceful temperament and interesting behavior.

These fish feed primarily on algae and aufwuchs, which is a growth of microorganisms that generally accumulates in the spaces between rocks. They feed by scraping this off with their specialized teeth called “pharyngeal teeth” located in their throat. The fish eat both green film algae as well as brown diatom algae, almost exclusively when living in the wild.

The otocinclus catfish is very similar to and often confused with its relative, the oto catfish (Pseudotothyris janeira) which also feeds on algae and aufwuchs, living in South America. However, one way you can tell them apart is by looking at their eyes. The oto catfish has eyes that are far apart, while the otocinclus’s eyes are positioned closer together.

Species profile

Otocinclus catfish

The otocinclus catfish, also commonly known as the “dwarf sucker” or “Oto”, is a small freshwater fish that is popular among aquarium hobbyists. This species can be found in slow-moving streams and tributaries of the Amazon River Basin in South America. They are typically olive-green in color and have a dark spot on their dorsal fins.

Range and habitat

The otocinclus catfish is a tropical fish and can be found in South America near the Amazon River Basin. They live in slow-moving streams and tributaries where they feed on algae.

They are very small, typically only reaching lengths of around two inches. Despite their small size, they are an excellent algae eater and will help keep your aquarium clean.

Brichardi Fish Care - Fairy Cichlid

Otocinclus catfish size

The otocinclus catfish can grow to a size of three or four inches.

Keep one or more?

One to three otocinclus catfish should work well for most setups that keep between five and fifteen gallons of water. However, you may need to add up to four or five otocinclus catfish to really keep your tank clean and algae-free.

Otocinclus catfish tank size

Otocinclus catfish can be kept in a tank as small as ten gallons, but they will do better in a larger tank. A twenty-gallon or larger tank is ideal.

Tank setup

Your otocinclus catfish will need a tank that is at least 20 gallons in size. The water should be kept between 74 and 80 degrees Fahrenheit, with a pH of around six to seven. You’ll also need to provide plenty of plants for your catfish to hide in and graze on.

You can either use an artificial or live plant. If you choose to use an artificial plant, make sure it is free of any chemicals that could be harmful to your catfish. If you’re using a live plant, be sure to rinse it thoroughly before adding it to the tank. You can also attach the plant to a rock or driftwood with some fishing line or thread.

You’ll also need to provide a good amount of filtration and aeration to your tank. A filter that can handle up to 100 gallons per hour is ideal, but any filter rated for up to 50 gallons per hour should work fine.

And finally, you’ll need to add some algae tablets or wafers to your tank. Otocinclus catfish love to eat algae, so these will help keep them healthy and happy.

Otocinclus catfish tank mates

Otocinclus catfish can be kept with a variety of different fish, but it’s best to avoid keeping them with any fish that are known to be aggressive. Some good tank mates for otocinclus catfish include Platies, Mollies, Zebra Danios, White Cloud Mountain Minnows, Neon Tetras, Corydoras Catfish, and Banana Shrimp.

Just be sure to do your research before adding any new fish to your tank, and make sure they are compatible with one another.

How many Otocinclus catfish should be kept together?

One Oto catfish per one gallon of tank water is the recommended minimum. More than that will stress them out and could lead to aggression problems between your fish, which may cause at least one death in the group.

Life cycle

Otocinclus catfish spawn in the wild on a seasonal basis, typically from August through December. In the aquarium, however, it is more common for them to breed all year round. It doesn’t take much effort at all on behalf of the aquarist to induce spawning either, with an increase in water temperature being enough in most cases!

The Pygmy Sunfish "Elassoma Evergladei"

The eggs will be laid amongst the aquarium plants, with both the male and female fish participating in guarding and caring for them. The fry will hatch within a few days and will be able to feed on newly hatched brine shrimp straight away.

Are they aggressive or peaceful?

Otocinclus catfish are peaceful fish that get on well with most other species of fish. They will however defend their territory if they feel threatened.

Otocinclus catfish care

Otocinclus catfish

Otocinclus catfish are very easy to care for and can be kept in a wide variety of aquariums. They require a well-oxygenated tank with plenty of plants and should not be housed with aggressive or large fish.

The water temperature should be maintained between 22 – 26 degrees Celsius and the pH level between neutral and slightly acidic.

They can be given a variety of food.

What do Otocinclus catfish eat?

Otocinclus catfish can be fed a variety of food, but should primarily be given algae wafers or tablets.

They also enjoy fresh vegetables such as peas and cucumber which they will relish alongside Spirulina flakes. They cannot eat whole fish so ensure any uneaten foods are removed from the tank before it starts to decay.

They will accept live brine shrimp, but only occasionally as they are not carnivores by nature and some specimens may refuse to eat them at all.

Water conditions for Otocinclus catfish

Otocinclus care is relatively simple and they will thrive in most aquariums. However, you should use a well-oxygenated tank with plenty of plants to ensure their comfort and provide them with the algae that make up the majority of their diet. They can be kept at a temperature between 22 – 26 degrees Celsius and a pH level between neutral and slightly acidic.

The water should have a general hardness of around 12 dGH, with a minimum recommended value being set at about half this figure. A higher value can be tolerated as long as it does not exceed 25 dGH, but it is important to bear in mind that they are from soft water habitats.

They are very sensitive to changes in water chemistry and quality, so regular small daily water changes of up to half the tank volume should be used as a preventative measure against disease or contamination. This will also help keep the nitrate levels low – another factor that must be kept within acceptable limits for their health.

Otocinclus catfish breeding

Otocinclus catfish

Otocinclus catfish are not often bred in captivity, but it is possible to do so with a little bit of effort. The key is to provide them with an environment that closely resembles their natural habitat.

The breeding tank should be heavily planted and include driftwood and other hiding places. It should also have a strong current as they like to swim in open water. The temperature should be maintained at around 26 degrees Celsius and the pH level between neutral and slightly acidic.

Platystacus cotylephorus (Banded Banjo Catfish)

The breeding process begins when the male starts courting the female by swimming alongside her and nudging her gently with his head. If she accepts his advances, she will release her eggs which he will then fertilize. He will then carefully collect them in his mouth and place them on a suitable surface such as a leaf or piece of driftwood.

The eggs will hatch within two to four days and the fry can be fed newly hatched brine shrimp or powdered flake food. They should be moved to their own tank once they are large enough to avoid being eaten by the adults.

Lifespan of Otocinclus catfish

Otocinclus catfish have a lifespan of around three to four years in the wild. In captivity, they can often be expected to live for longer – some specimens have been known to reach the ripe old age of eight.

Their long life is partly due to their low maintenance requirements and partly due to the fact that they are not as susceptible to disease as some other fish species. However, they should be kept in good condition and their water quality monitored regularly to ensure a long and healthy life.

Parasites and diseases

Like all fish, otocinclus are susceptible to parasites and diseases.

The most common parasites include:

  • Ichthyophthirius multifiliis (ich): a protozoan parasite that causes white spots on the skin of the fish
  • Cryptocaryon irritans (marine velvet or saltwater Ich): another protozoan parasite that can cause severe damage to the gills
  • Anchor worms (Lernaea cyprinacea)
  • Oodinium pillularis (velvet disease or gold dust disease): attacks the skin, fins, and sometimes internal organs of fish. Velvet diseases are usually caused by poor water conditions
  • Pseudomonas fluorescens: a bacterium that can cause ulcers on the fish’s body

The most common diseases include:

  • Mycobacteriosis: a bacterial infection that affects internal organs, often causing death. The bacteria is resistant to many antibiotics and there is no known cure
  • Columnaris: a bacterial infection that causes the appearance of “cotton wool” around the mouth, fins, and gills
  • Dactylogyrus spp. (gill maggot or fish lice): a parasitic flatworm that attacks the skin, gills, and sometimes internal organs
  • Vibrio anguillarum: another bacteria which affects the intestine and can cause death
  • Enteric septicemia: a serious, often fatal infection caused by bacteria that affects the gut

Any of these parasites or diseases can be potentially deadly to your otocinclus, so it is important to take steps to prevent them.

Otocinclus catfish dying

Otocinclus catfish are great for beginner aquariums. Not only do they help clean the tank, but these little guys provide hours of fun entertainment! If you have experience with keeping fish before it’s likely that your first choice for an algae eater was one of these little cuties. However, what happens when instead of helping keep the tank clean, your otocinclus starts to die?

Redear Sunfish (Lepomis microlophus)

There are a few things you can do if your otocinclus catfish is dying. The first step is to test the water parameters and make sure that everything is in balance. Otocinclus thrive in slightly alkaline water with a pH of around seven and moderate hardness. If your tank is not properly balanced, this could be the reason why these fish are dying instead of helping keep the tank clean. The next step would be to check for possible injuries or wounds on the fish and treat them accordingly if needed.

The final thing you can do to prevent further loss of life in your tank is to use a medication such as Maracyn Plus. This product contains both of the active ingredients found in Maracyn and Maracyn Two which are used for treating things like fin rot, tail rot, mouth fungus, and dropsy. Another thing this medication does that other medications do not is it treats gram-negative and positive bacteria infections making it great for treating things like fin rot and tail rot.

Otocinclus catfish dying is something that can be prevented if the water parameters are checked on a regular basis, possible injuries or wounds treated accordingly, and finally using an effective medication.

Predators of otocinclus catfish

While otocinclus catfish are great for helping to clean the tank, they can also fall victim to certain predators in the aquarium. Some of these predators include other fish such as cichlids and barbs, as well as invertebrates like snails and shrimp. If you are seeing your otocinclus catfish dying and know that the water parameters are in balance, then it is quite possible that they have fallen victim to one of these predators.

If your tank has cichlids or barbs you should be very cautious about adding an otocinclus because if not given enough hiding places they will become easy prey for these fish. If you have invertebrates in your tank, like snails or shrimp, then be sure to provide plenty of places for the otocinclus catfish to hide. This will help keep them safe from being eaten by these predators.

Do they make good pets?

Yes. Otocinclus catfish make great pets for those who are just starting out with keeping fish. They are very low maintenance and can easily be cared for. They also provide hours of entertainment as they dart around the tank looking for food.


Though they are small, otocinclus catfish make a big contribution to the health of your aquarium. They scavenge for food and remove algae, making your tank healthier and more attractive. If you’re looking for an easy-to-care-for fish that will help keep your tank clean, otocinclus catfish are a great choice.