Fremen, CC BY-SA 4.0, via Wikimedia Commons

The Oto Catfish or Otocinclus is a genus of small and beautiful fish species known for their algae eating habits and peaceful nature. Fish from this genus are sold under multiple names such as Oto fish, Oto Catfish, Otocinclus Catfish, Ottos, Dwarf Sucker, Dwarf Suckers, Algae Scrapers, and many other names. All of these are different species of fish from the same genus. It is one of those fish species that are especially good for the new fish keepers. It is because these fish species do not require intensive care.

It is a beautiful fish species to have in your aquarium. These peaceful creatures would live peacefully in your aquarium and would wander around and explore everything with curiosity and would bring life into your aquarium. Also, they are a peaceful fish species, meaning that they can be paired with other peaceful fish species in community aquariums. It is a freshwater species from the Loricariidae family of fish. In this genus, 19 different fish species are considered in the same category. But each one of them has different features such as different sizes, shapes, and coloring. Most of these species are known as Otto’s or Dwarf Sucker, which happens to be the most common name that is used for this group.

This species of fish is native to South American rivers in Argentina and Venezuela, but they are not usually found in the Amazon river. There are a lot of reasons for putting them in your tank, including the fact that they are a beautiful fish species that would bring beauty and life to your aquarium and will also clean your aquariums. They are algae eaters, meaning that they would clean the water from algae and prevent algae-based water pollution. The article below contains proper care information about these fish species.

Basic Facts Table:

Lifespan3 to 5 years in perfect conditions, less than 3 years in the wild.
SizeUp to 2 inches
ColorsDark, Brown, colorful stripes.
DietOmnivores, Algae Eater
Freshwater or SaltwaterFreshwater
Care LevelMinimum, Beginner Level.
CompatibilityPeaceful Communities.

Tank Companions:

The Otocinclus Catfish are mostly peaceful fish species, meaning that they can be paired with other peaceful fish species of small size. Normally, they live peacefully and quietly with most of the species, but if their number is large in a community aquarium, they will become hyperactive. For that reason, if you are adding them to a community tank, make sure that the number of other fish species is appropriate. It is recommended to pair them with other peaceful fish species and avoid pairing them with aggressive fish species. Here is a list of species that you can pair with the Otocinclus Catfish.

  • Dwarf Gourami
  • Zebra Loaches
  • Small Mollies
  • Small Guppies
  • Cherry Barbs
  • Small Tetras
  • Corydoras Catfish
  • Harlequin Rasbora
  • Amano Shrimp
  • Cherry Shrimp

All of these peaceful fish species can live in the same aquarium peacefully because they are almost the same size and have the same peaceful nature. Below is a list of the species that you should not pair with the Otocinclus Catfish.

  • Most Cichlids
  • Feisty Oscars
  • Large fish species,
  • Any aggressive fish species.


Cisamarc, CC BY-SA 3.0, via Wikimedia Commons

The Otocinclus Catfish are small and only reach about 2 inches in size. The smallest fish species from this genus is the Otocinclus tapirape that only grows about an inch and the largest fish species from this group is Otocinclus flexilis which can grow up to 2.2 inches. Most fish species from this genus have cylindrical shapes, and their head part is narrow as compared to the middle part of their bodies. These species use their mouth to latch onto surfaces apart from eating food. They do this because their mouth is shaped in a way that helps them do it. It can suck air into the body and create a vacuum between the mouth and surface. This vacuum helps it latch on these surfaces.

These fish species also have armor around their bodies that they use for protection when attacked. The male and females from these species mostly look the same, the only known major difference is that the females are broader and larger while the male is comparatively smaller. This identification of the sexes helps during the time of breeding.

As mentioned earlier, there are more than one species in this genus and each one has a slightly different appearance. Below is a guide about the list of species and their appearance.

List of Species in Otocinclus Genus:

As mentioned in the paragraph that this is not a single species of fish but a genus of fish. There are about 19 different fish species in this genus. Each of these has a different size, shape, and color pattern. Some of them are not as beautiful as the others and that is why some of them are most commonly known. These known species are used in aquariums. Here is a list of all of the species in this genus.

  1. Otocinclus arnoldi
  2. Otocinclus batmani
  3. Otocinclus bororo:
  4. Otocinclus caxarari
  5. Otocinclus cocama
  6. Otocinclus flexilis
  7. Otocinclus hasemani
  8. Otocinclus hoppei
  9. Otocinclus huaorani
  10. Otocinclus juruenae
  11. Otocinclus macrospilus
  12. Otocinclus mangaba
  13. Otocinclus mariae
  14. Otocinclus mimulus
  15. Otocinclus mura
  16. Otocinclus tapirape
  17. Otocinclus vestitus
  18. Otocinclus vittatus
  19. Otocinclus xakriaba

Out of these 19 species, only 5 are Here is a list of the common aquarium fish species from this genus.

  • Common Otocinclus (Otocinclus vittatus): It is one of the most common species from this genus that is found almost everywhere. This fish species has a beautiful shape, coloring, and peaceful nature. It is naturally found in the South American rivers, ponds, lakes, and freshwater aquifers. This fish has a beautiful brown speckled pattern on its body that makes it unique. Its body is elongated, thin, and cylindrical which helps identify them. Also, their bodies are covered with blackish spots that go from head to back.
  • Zebra Otocinclus (Otocinclus Cocama): It is also one of the most common Otocinclus species. It is known for its black and white stripes, hence named the Zebra Otocinclus. Other names of this fish species include Tiger Otos because the black and white patterns in their bodies are not perfect. You can easily identify them with the help of these black and white stripe patterns and their cylindrical body shapes.
  • Golden Oto (Otocinclus affinis): Golden Oto is known for its algae eating habits and beautiful golden color pattern. The dark body of this species is covered with golden stripes and spots. It likes to live in large schools and is mostly found in the shallow areas of the rivers in South America. Because of the gold stripes all over the body, it is known as the Golden Oto which helps identify them out of the pool of other Otocinclus catfish.
  • Silver Otos (Otocinclus vestitus): the shape of this fish species is similar to the common otocinclus fish species but has different coloring patterns. This coloring pattern makes it unique among the group. It is one of those fish species that are commonly found in aquariums. Their silver bodies are covered with slightly dark and brownish spots and stripes that make them easy to spot in the tank.
  • Dwarf Oto (Otocinclus macrospilus): this fish species is known with many names but the Dwarf Oto is its most common name and is often used in the fish trade. This is a freshwater fish species that like to live in shallow waters where the flow of the water is slow. It is a native South American river. Dwarf Otos have brownish spots all over their bodies and these spots help identify them.

These were the appearance details of one of the most famous Otocinclus Catfish species. These details can be used for identification purposes. Although these details are not complete because most of the species from the list above are not found in any aquarium. That makes it almost impossible to get the exact information on each of the specimens of these species. But with the help of these general appearance details, you can easily spot them.

Origin and Natural Habitat:

The Otocinclus Catfish are native to the small rivers, lakes, and lakes in South America. Oddly, these species are not found in the Amazon River, which flows through almost the entire continent. Instead, these species are found in different small rivers that flow through the South American countries. These fish species are bottom feeders, meaning that they eat their food from the bottom of these rivers.

Otocinclus Catfish prefers to live in places where the flow of water is extremely slow. These are small fish species and they eat while they are latched to the stones in the bottom of the river. So, if the flow of the river is fast, they would not be able to latch on to these stones and it would starve them. That is why they like to live in such places. The temperature of the water in these areas is also warm which favors their growth, and allows them to spawn and reproduce in large numbers. This helps them survive in the wild as they can reproduce in large numbers.

In the bottom layer of the water where these fish live, water is mostly neutral and is well-oxygenated. Most of the time, the places where this fish species stay it does not have any vegetation or underwater plants. That is why they live most of their lives near the rocks, and places where they can latch. Also, as these are shallow waters, they have access to light even in the bottom layers. Their unique color combinations help them evade predators by looking similar to their surroundings.

Otocinclus Catfish Lifespan:

As you know that there are multiple fish species in this genus and each fish species has its lifespan. Most of them can live up to a year or two in the wild conditions. But if the conditions are perfect and favor the growth, some can live for three, four, even five years. But if you want your fish to live this long, you will have to provide the perfect and most favorable conditions that they need.

There is no average lifespan for these fish as mentioned earlier there are more than one species. In this group, smaller fish species have a shorter lifespan and the bigger fish species have a longer lifespan. But with proper care, you can extend the lifespan of your fish in the tank by providing them with a perfect living environment that is similar to their natural habitat but does not contain any predators or potential causes of death and illness. With these strategies, you can extend the lifespan of your fish by a considerable amount.

Habitat and Tank Conditions:

If you are building a tank for your Otocinclus Catfish, you will have to start from the bottom layer of the tank. But before that, make sure to get a larger tank if you want to create a community aquarium. The ideal size of the tank is relevant to the number of fish and the size of fish that you are going to put in the tank. Keeping these in mind, you should pick an appropriate tank. Once you are done with the tank, you can start creating a habitat inside the tank for your fish.

The bottom layer of your fish tank for the Otocinclus Catfish is the most important, and you will have to focus more on this layer. You should start the preparation by putting treated sand inside the tank. Make sure that there is no dust inside the tank. Because if there is any dust, it would create a muddy water problem, mud would take some time to settle down in the bottom layer. After the sand, it is time to add substrate. You can use stones, and pebbles, make sure that they are clean, washed, and rounded. Do not use the stones with sharp edges to lay in the bottom of the tank.

After that, you can put some plants in the tank to make a healthy environment. You can also put some decorations in the bottom and the middle layer of the tank. These fish rarely visit the surface water and the middle layer. So, it will be okay if you do not put anything in that part. After you’re done with these, you will have to put a filtration system and a heating system inside the tank to keep the water warm and clean and to provide sufficient oxygen that these fish need. You will also have to work on providing them with light conditions. You can use two types of lights in these fish tanks. First, use a light that is hanging above the tank, or use a light that is submerged inside the tank.

Water Conditions:

After you are done creating a perfect bottom, middle, and upper layer of the tank, and have put filtration, heating, and lighting systems inside the tank. It is time to put some water inside the tank. Once you fill the tank with an appropriate amount of water, you will have to make sure that the water inside the tank has favorable conditions for your fish’s health. Certain water parameters must be followed in this step. Here is a list of these water parameters that need to be checked at this level before putting the fish inside the tank.

  • pH: Neutral is better
  • Hardness: less than 15dH
  • Temperature: 72-79°F
  • Filtration: 20 to 25% water/week
  • Size: 20 gallons

These are the ideal conditions that are similar to their native habitat. These measures will keep them healthy inside the tank and would let them live to their potential lifespan. But if these conditions are not met, or if there are changes in these conditions, it would negatively impact their health. For example, changes in water temperature would cause changes in their internal temperature, which can shut down their organs and kill them. Also, higher acidity or lower acidity inside the water would cause a chemical imbalance in the tank and that would directly impact the health of these fish as well. For these reasons, it is advised to keep the conditions perfect.

Water Source:

For the tank of Otocinclus Catfish species, you can use any type of water from any source. For example, you can use the water from the tap of your house, and you can buy special water for the aquarium. Both of these water will have similar compositions but tap water would have some additives and chemicals inside to make it safer for drinking. These additives harm the health of these fish and that is why it is recommended to remove these additives through reverse osmosis.

After the removal of these additives, water will be safer for the fish and you can add that into your tank. You should test the water before putting it in the tank to know the chemical composition, amount of minerals, and pH of the water. This valuable information that you will learn from testing will help you get better water for your fish so that they stay healthy and live longer.

Ideal Size For The Tank:

There is no single ideal size for the tank of Otocinclus Catfish. As you know that these are multiple species of multiple sizes. These species also have different pairing requirements and different numbers of individuals per school. You should know the minimum number of individuals for the school, and get a tank that can contain that many fish species.

For example, if the Otocinclus Catfish school size is 15, you will have to get a tank that can contain 15 fish, and if one fish needs two gallons of water, the size of the tank would be 30 gallons for the school of Otocinclus Catfish. The smallest tank that you can use for these species is the 10 gallons tank. Meanwhile, the most recommended tank size is the 20 and 30 gallons tank. Using the appropriate size of the tank for keeping your fish would help you avoid overcrowding issues.

Behavior and Temperament:

Otocinclus Catfish are generally known for being peaceful, shy, and less defensive. If they see a conflict or confrontation, they would run and try to hide. That is why you should not pair them with aggressive fish species as those would keep the Otocinclus Catfish species under constant pressure. As they are a peaceful species, pairing them with other peaceful species would improve the environment of your tank. Otocinclus Catfish tends to be social towards other species.

It would mix with them, and dart from one part of the tank to another with them if the other fish species are peaceful. Otocinclus Catfish show a grouping behavior. They tend to stick together with the other members of their species. You should not keep a single Otocinclus Catfish in a separate tank as it would stress that fish which can lead to health problems. A group of Otocinclus Catfish likes to stick around to different surfaces including the stones in the bottom, and also to the walls of the tank.

Breeding Otocinclus Catfish:

Otocinclus Catfish are some of the hardest fish species to breed. But with proper care and following a proper procedure, anyone can do it. If you are planning on breeding your Otocinclus Catfish, you will have to create a breeding tank for them with all of the above specifications. You will have to put the male and female inside the breeding tank and start feeding them a lot of food.

Raise the temperature in the breeding tank to a few degrees, this would depict their natural breeding time when the temperature is slightly higher than the usual in the wild conditions. Also, make sure that your new breeding tank is clean and has no contamination. During the time of mating, the male would chase the female and they would spawn.

The female Otocinclus Catfish would produce multiple sets of the eggs that are fertilized by the male in that tank. You should remove the male and female Otocinclus Catfish from the breeding tank after that as they would try to eat the eggs. After that, just wait for the eggs to hatch.

Eggs and Fry Care:

Keeping the male and female away from the eggs is important as it would allow the eggs to hatch and would prevent them from being eaten. After that, fry would come out of these eggs once they hatch and the fry would start to eat the egg sack. After that, the small fry would be able to swim and reach the bottom layer where it would eat algae and small insects. They gain a considerable size within a few days.

Diet of Otocinclus Catfish:

The diet of Otocinclus Catfish is omnivore in the wild. They eat everything, from algae to small invertebrates, and insects. But algae acts as a major source of their food in those environments. So, if you want to provide your Otocinclus Catfish with a healthy diet, you should include algae flakes, fresh and frozen insects, and live worms in its food. Feeding them twice every day is enough.

Diseases of Otocinclus Catfish:

The Otocinclus Catfish are immune to most of the fish diseases and can deal with them on their own. But there is one major disease in these fish species that requires special attention and treatment. This disease is known as the Ich. Here are details about it.

  • Ich Disease: Ich is a parasitic disease that causes infection in fish. It is highly contagious and if you see any fish with white spots in your aquarium, you should quarantine it and treat it with recommended medicines for this disease.

Your Otocinclus Catfish species would remain healthy for most of the time, unless your tank is not cleaned properly or if there are changes in the parameters inside the tank. So, you should focus more on keeping the environment favorable and healthy for them and you will not have to worry about diseases.

Is Otocinclus Catfish a Saltwater or Freshwater Species?

Otocinclus Catfish species are freshwater fish species.

Is Otocinclus Catfish a schooling species or not?

Yes, these are schooling fish species. The smallest size of their school is six and the largest size of their school is 15. Otocinclus Catfish like to stay close to each other and that’s why they latch together on the surface of the tank, and also on the walls. Apart from that, you will also see them schooling through your tank.

Conclusion – Is Otocinclus Catfish Suitable For Your Aquarium?

The simple answer to this question is yes, these are suitable for your tank, and here are the reasons for that. First of all, these are beautiful fish species that would beautify your tank. Secondly, these are schooling fish species, so, you will be able to enjoy watching their school move in the tank. The third reason is that these fish are easy to take care of even if you are new at fish keeping. Otocinclus Catfish do not require extra attention and you will only have to give them a few minutes. These are the reasons why the Otocinclus Catfish are suitable for your aquarium.


Question: What is the lifespan of Otocinclus Catfish?

Answer: Some of the Otocinclus Catfish can live up to five years in the tank while others only live up to three years. The exact lifespan depends on the species of fish and the conditions inside the tank.

Question: What is the ideal tank size for Otocinclus Catfish?

Answer: The smallest tank that you can use is the 10 gallons tank for the aquarium of Otocinclus Catfish. But it is not recommended, the most recommended tank size for a school of Otocinclus Catfish is 20 to 30 gallons tank.

Question: What are the ideal tank mates for Otocinclus Catfish?

Answer: Here is a list of the ideal tank mates for the Otocinclus Catfish, Rasbora, Mollies, Tetras, Corydoras Catfish, Danios, Dwarf Gourami, Guppies, Harlequin. Zebra Loaches, Angelfish, and Cherry Barbs.

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