Otocinclus: Facts, Lifespan, Care, Feeding, & Breeding

The dwarf suckers are one of the most popular algae eaters. You can say it is the little fish that cleans up after itself. The otocinclus is a catfish that is referred to by several names. Other than the dwarf sucker catfish, they are also known as cascudinhos, ottos, or algae scrappers.

The size of the may be small, but it demands a lot of attention and care. A fish such as the otocinclus is susceptible to water, so it is ideal to get clean water with the proper conditions. For instance, the pH, temperature, and hardness of the water must be correct and maintained every time needed.

Sadly beginners aren’t fit enough to maintain a dwarf sucker unless advised or mentored by an expert in otocinclus rearing.  

Interesting facts about dwarf suckers

They are bottom dwellers

The otocinclus catfish are bottom dwellers that feed on algae. They also scavenge on leftovers dropped by fishes in the upper stratus of the tank. This is very beneficial to them as they are very peaceful. There is no need to compete for food or territory as a lonely bottom dweller.

They are not messy

The otocinclus catfish is an algae eater. It eats algae off the tank’s environment. The fish indirectly helps the owner in cleaning the tank.

Physical description

The otocinclus has an elongated body with flattened sides which is covered with broad boney scales all over the body except the abdomen. Their eyes are large, along with the face you will see they possess a cupule-shaped mouth.

This catfish has the respiratory organ meant for breathing atmospheric oxygen which aids intestinal respiration of the otocinclus. The hue of the fish consists of a yellowish tint and a wide black stripe along its long slightly flattened body. The fins of the otocinclus are colorless with some shades of green.

Size and lifespan

An otocinclus catfish is a small fish that can grow the max of 2 inches. A normal one is about 1-5 inches. Its small size is of great advantage because it allows them to swim fast, therefore evade predators. They are so fast they could dart in seconds from one end of the tank to the other.

With right conditions, the otocinclus catfish can live for 3-5 years tops. Only if it is in a well-conditioned water tank and with good feeding. But in the wild, the story is different. The otocinclus catfish are easy prey due to their peaceful nature. They tend not to fight other fishes for food, mater or space. They usually just run away from a threat. If not fast enough they get preyed on. 


The ottos are known to be peaceful fishes that can get along easily with other fishes. They are so peaceful; plant life is speared in the aquarium if fed well. A fish with this calm is perfectly compatible with other fishes that share the same temperament.

Avoid keeping a dwarf sucker catfish in the same tank with an intolerant and aggressive fish such as the crown fish bettas which are known to be very aggressive when it comes to space, food, and mate. It is best to keep the ottos in schools with other peaceful fishes that are willing to co-exist

Otocinclus Tank Mates

When choosing the perfect tank mate for a particular fish, there are certain things to consider. The tank condition is one of them, and it should be taken seriously as the water condition for the primary fish may not be right for its tank mates.

Another to consider is the temperament of the fish. It is best to know if the fish is aggressive or not. If it is aggressive, what is it aggressive for? Is it a mate? Is it food? Or is it territory? Also, find out which stratus of the water it swims in?

Here are some fishes to consider which actually checks out the boxes: 

•    Cory catfish – this is a very active freshwater fish which is peaceful and non-aggressive. They are shy and timid. This makes them a good tank mate for an otocinclus. Its active and playful behavior may even rub off on the otocinclus catfish. Also, the Cory catfish are bottom dwellers, just like the dwarf sucking fish (otocinclus).

Cory Catfish Source

•    Bamboo shrimps – This fish has no claws or pincers to defend itself. They are harmless to other tank fishes. Although, its lack of weapons is not the reason why it’s harmless. The reason is that its nature is peaceful, just like the dwarf sucking catfish. This makes the bamboo shrimp a good tank mate for the dwarf sucking catfish.

Bamboo Shrimp Closeup
Bamboo Shrimp Source

•    Snails are also a good candidate – nerite snails, Malaysian trumpet snails, ivory snails, rabbit snails, gold Inca snails, Ramshorn snails, mystery snails, and Japanese trapdoor snails.

Elephant Snail
Rabbit Snail Source

•    Apart from the bamboo shrimps, there are other to consider such as the vampire shrimp, Amano shrimp, ghost shrimp, and red cherry shrimp.

Fishes to not consider

Keep these fishes away from the dwarf sucking catfish. The fishes on the list below are very aggressive and can prey on the dwarf sucking catfish.

•    Goldfish

•    Cichlids

•    Roughens (Oscar, Jack Dempsey striped convict, and Texas cichlids)

There other fishes not mentioned on this list. Make sure to look up the species compatibility before considering them as tank mates.


The otocinclus natural habitat can be found in small or middle-sized rivers with moderate flow. The location of such streams is in Colombia. They can also be found in the northern parts of Argentina, Peru Brazil, and Paraguay.

Tank conditions

It is advisable to have a tank with a capacity of 7 gallons which is big enough to contain four catfish. If you wish to have more than 15 fishes in the tank, the perfect size should range between 26 – 42 gallons.

To start, you will need an effective water filter that has the ability to renew the whole amount of water three times within one hour. The filter must also be able to decrease the level of ammonia or nitrates in the water.

When renewing the tank’s water, it is best to replace only about 30% every week to reduce the level of ammonia or nitrates and at the same time keep the water in good condition. Renewing the whole tank can lead to the stress of setting up the water condition anew.

The perfect temperature for the tank is within the range of 22-28 degree Celsius and the pH balance of the water must be a bit acidic or completely neutral.

Otocinclus Tank Accessories

Once the water conditions are achieved, the otto catfish will be able to live in the tank comfortably. The tank would feel like its natural habitat. Note that the otocinclus catfish prefer to live in large shoals, so it is only right to buy them. There should be at least six shoals in the tank.

These shoals are optional. They are to help make the tank feel a lot natural for the otocinclus catfish. If you can afford them go ahead, as long as it fits into the tank’s water capacity.

Vegetation such as oak tree roots, tough tank plants, preliminary soaked tree branches, small leaves, and other underwater plants. Along with the plants, there should also be a round stone that catches algae.

The inclusion of all these would make the experience of the otocinclus catfish similar to what it would experience in its natural habitat. 


If a well-fed otocinclus catfish was taken from the wild and then cut open, it will be discovered that its stomach is filled up organic substances and algae. As they are its favorite dishes of any day. The same would be discovered in a well-fed tanked otocinclus catfish.

The otocinclus catfish does not only depend on algae for nutrition. Try to prevent cheating this algae eater when it comes to feeding. Other dishes should be added to the menu if you wish to keep it well fed and happy.

The otocinclus catfish can be fed certain vegetable feeds such as spirulina, frozen bloodworms, flakes, and gammarid. Also, freshly steam vegetables can be great as feed. They include lettuce, squash, spinach and green peas. These will be a great diet for the otocinclus catfish.

How to prepare steam vegetables for the otocinclus catfish

Otocinclus feeding on veggies Source

The veggies should be boiled for about two minutes or to make things faster they should be placed in a microwave oven for 30 seconds. Once that is done, place the boiled veggies flat on the rock in the Water tank. This way the otocinclus catfish will feed comfortably.

How frequent should you feed them?

They can be fed once a week, provided the meal is adequate for their little stomachs. The leftovers in the tank should be removed in 2 days in order to reduce the build-up of ammonia or nitrates in the water.

 Feeding once a week is ok, given the fact that otocinclus catfish feed also on algae. Before the next feeding session, the algae might feed on enough algae.     

Breeding the otocinclus catfish

The process is quite hard as the fishes tend to be picky. That is why it is best to keep a group of fishes in the breeding tank as a suitable partnership would be found. Before breeding begins it is best to know which it is.

How to determine gender?

The otocinclus catfish are known to show a pronounced sexual dimorphism where the female fish tend to become larger and wider than the male after they fit for reproduction.  Another way to tell from the two genders is that the male fishes possess genital papilla and rows of modified denticles. Those two are located on the bottom side of the fish’s tail-stem.


The breeding process begins with the male pursuing the female. If the male is lucky it would get in a “T” position with the female. This position will cause the female to release and hold her eggs with her ventral fins. The female will then look for a suitable spot to put the eggs so the male can begin fertilization.

The process continues until the female releases all her eggs. After fertilization, the male is done with his job. There will be no guarding of the eggs by the male because the otocinclus male catfishes do not guard the eggs like other fishes. 

The process of mating is usually time-consuming, to even catch them mating is sometimes rare. In order to make the process quick, the fishes should be feed with a high protein diet that consists of live feeds. And they should be fed several times a day.

Overview of how to raise an otocinclus catfish

The maintenance of an otocinclus catfish can be easy. The basic needs for its growth and health must be met and can be stressful sometimes.

•    The tank’s size must be with the range of 20 -30 gallons, depending on the number of fishes in the tank.

•    30% of the water should be renewed every week and the temperature of the water should be within 70-78 degree Fahrenheit.

•    The pH of the water should be kept within a range 6-7.5. Also, the hardness of the water should be with a range of 6-15 degree dH.

•    The otocinclus catfish are known to love company, a school of three or five is perfect.

•    The tank should be heavily planted with enough leaves, roots, branches rocks and shoals so it would feel more at home.

•    They are mainly herbivores so it is best to feed them vegetable base meals and algae.


The otocinclus catfish is a great pet to have in your tank, especially when the tank is heavily planted and with no bottom dwellers.  When purchasing this fish make sure to take a good look at their appearance – does it have a good color? How does it fins look? Does it have a plump belly or a bloated one?