Otocinclus Catfish: Ultimate Care Guide

Common Name(s)Otocinclus, Otocinclus Catfish, Oto Catfish, Oto fish, Dwarf Suckers
Scientific NameOtocinclus arnoldi Otocinclus batmani Otocinclus bororo Otocinclus caxarari Otocinclus cocama Otocinclus flexilis Otocinclus hasemani Otocinclus hoppei Otocinclus huaorani Otocinclus juruenae Otocinclus macrospilus Otocinclus mangaba Otocinclus mariae Otocinclus mimulus Otocinclus mura Otocinclus tapirape Otocinclus vestitus Otocinclus vittatus Otocinclus xakriaba
OriginSouth America
Temperature74°F to 80°F (24-28 ºC)
Size1-2 inches
Minimum Tank Size20 gallons
Food & DietHerbivore
Lifespan3 to 5 years
Water pH6.8 to 7.5
Tank MatesTetras, boraras, rasboras, barbs, mollies, and shrimp.
BreedingEgg Layer
Common DiseaseMay be susceptible to cotton mold, white spot disease, gold dust disease, and roundworms.
Otocinclus Catfish

One of the kindest fish you can get for your tank is the otocinclus catfish.  This docile fish is a great addition to any aquarium because they are so sweet and do not have a mean bone in their tiny bodies.  They get along with all other aquatic creatures and never cause a fuss.  They are popular because you can add numbers to your tank without any risk of them showing aggression. 

Nearly twenty different species of otocinclus catfish have been recorded, but not all types of these fish make it into an aquarium.  The ones that do end up in an aquarium are often difficult to tell apart.  When you buy one from a store, it will often just be labeled as a “general” otocinclus catfish.  All the different types are found in similar environments and water conditions because they all come from multiple areas of South America, including many parts of the Amazon basin.  They tend to hide in dense vegetation in small rivers and streams.

The otocinclus catfish is a very peaceful fish that like to stay in groups.  So consider buying a number of them for your tank.  From the Loricariidae family, the otocinclus catfish has made its way into the aquarium hobby more and more over the past few decades.  The problem is that your average hobbyist probably can’t tell which version of the otocinclus they have.  Their general appearance resembles that of a tabby cat with spots and speckles of brown, black, and white.  Their appearance helps them blend into the substrates of the streams that they would occupy in the wild.  The freshwater otocinclus catfish are pretty fast swimmers, so be sure to get a good look at them when they are hanging out above the substrate.

Are Otocinclus good algae eaters?

Otocinclus are herbivorous and their main diet is made up of algae and slime that collects on objects in the area.  You may be a bit shocked to see their mouths, but don’t worry.  The otocinclus catfish eat the algae that builds up in the tank and form tight circles with their mouths in order to suck at any surface they attach with strength and tenacity that is quite surprising given their tiny size.  These otocinclus have a voracious appetite for hair algae especially and will keep it from taking over your tank.  Hair algae is one of the most common types of algae that are found to grow in aquariums and they can be a major problem for your tank if they get out of control.  While otocinclus catfish will eat any variety of algae that is presented to them, they will eat hair algae in particular if it is available to them.    

However, otocinclus will not touch brown algae or black bread.  It is not very beneficial to them and they seem to like algae that smells like garlic.  Therefore, it is best to stick with the hair algae as much as possible.  It is also important to remember that these fish are algae eaters and take care of the other fish more than they take care of themselves. 

Otocinclus Care

Otocinclus catfish are fairly easy to take care of, as long as you are keeping a good eye on your tank and all the elements within it.  Like with any fish, the water levels, upkeep of the tank, and correct feeding parameters are paramount to any fish’s survival.  As long as you follow these easy tips on caring for the otocinclus catfish, yours will thrive in its environment and add a pleasant sight to your tank. 


The water temperature for the otocinclus catfish needs to stay between 74°F to 80°F (24-28 ºC).  This temperature mimics the environment they would have in the wild.  Any sudden changes to the temperature of the water could produce serious health problems to your fish, so make sure you are monitoring your water’s temperature.  This warmer, slow-flowing water calls for a more neutral pH at about 7, but needs to stay in the range of 6.8-7.5.  Otocinclus do not do well in hard water either, so shoot for soft water with a reading of about 15dH. 

Otocinclus Size

Otocinclus catfish are small creatures with the largest species being about 2.2 inches.  Generally speaking, though, most types are between one and two inches long.  Because of their small size, they are not very strong breathers, which means they are less suitable for swimming vast distances. 

Food & Diet

Since otocinclus catfish are freshwater fish and are considered herbivores, you must recreate that in your own tank.  These fish are algae eaters in the wild and will be in captivity as well.  There are many types of algae wafers, which make incredible supplements.  You can also use any fresh vegetables that you might have in your house.  For example, lettuce pieces, Brussel sprouts, and spinach are good substitutes for algae, however, you must be sure to clean out any leftover pieces from the soil otherwise it will start to affect the aquarium conditions.  But whatever vegetable you decide to give them, be sure to wash it thoroughly to eliminate any insecticides and pesticides present on them.  It is ok to feed the otocinclus catfish once per day, but just keep an eye on the extra food and the algae growth inside.

Otocinclus Lifespan

Any loyal hobbyist is going to tell you that a fish’s lifespan is going to depend greatly on how well the owner of the aquarium takes care of the aquarium’s upkeep.  The very specific parameters listed in this article are the best conditions for keeping your fish and it is up to you to keep those parameters in check.  Sadly, no matter how well you keep your tank, the otocinclus catfish do not live as long as you might like.  They will inhabit your aquarium for anywhere between 3-5 years in the best conditions. 

Tank Size and Setup

When considering tank size, you will first need to consider what else you are putting into the tank.  If you are only going to put the otocinclus catfish into your tank, then you could stand to use a ten-gallon tank.  However, if you are planning on giving them some tank mates, then the minimum tank size would actually be twenty gallons.  Remember that these catfish must be in groups of three or four to reduce loneliness within the fish.  Having them in groups also will make them more playful and reduce their stress.  Therefore, you can have 4-6 of them in a ten gallon and they should be fine.  Furthermore, it is best to use a rectangular tank shape because the otocinclus catfish are bottom feeders and this shape will increase the surface area of the water.  There is also a better exchange of air and water ensures better health for your fish and can improve the quality of your water.  They can live in circular or vertical tanks as well, but rectangular is best.  Planning out your aquarium beforehand will help avoid any issues, plus, you will get to choose how you want to setup your tank. 

As for what is going inside, you should provide a solids substrate since the otocinclus catfish like to hang out at the bottom of the tank.  Some fine-grained sand would be perfect fit for these fish.  Anything larger-grained can actually hurt the otocinclus.  You should also add some rocks and plants because they will provide algae for the fish.  Leave enough room along the bottom of the tank for the little otocinclus catfish to swim around but provide some nice surfaces down there as well. 

Otocinclus Breeding

If you are wanting to breed the otocinclus, you may have a bit of difficulty doing so because of the complicated conditions that the otocinclus need in order to breed successfully.  Things like lighting and water conditions will affect the success of the breed.  After separating a male and a female into their own private tank, the female will start leaving small bunches of eggs all over the tank’s surface.  The male will then go around and fertilize the eggs and they will stay incubated for only a few days.  After that, fry will be swimming around the tank with mom and dad.  You will need to make sure that the conditions of the tank are suitable for these new fry.  Change the water by 50% every week and make sure you are using at least 75-80 liters of water for your breeding tank.  The fry will eat the bacteria and algae, as they will eventually start looking for the same algae as the adults. 

Females tend to be much larger and wider than the males and their sex organs are distinctively different.  Males have genital papilla with rows of modified dentils along the side of the tail.  This organ helps orient the male in the breeding process. 

Otocinclus Disease

These little otocinclus catfish have a particularly delicate immune system, so you should really keep an eye on them and look for symptoms of their failing health.  Anything like a reduced appetite, or lethargic behavior, heavy breathing, or just general inactivity might be warning signs that your otocinclus have some sort of health issue.  Make sure to check all parameters of your tank are at the right levels, especially the chemical levels.  If it seems to not be the tank machinery, then you may want to check out the fish for fungal or parasitic infections.  Assuming you keep a clean tank, the otocinclus should stay free od disease, but they can develop fungal problems.  Otocinclus catfish are known to have to deal with cotton mold, white spot disease, gold dust disease, and roundworms.  You can mix levamisole and parachlorometaxylenol to treat the diseases. 

Otocinclus Temperament and Behavior

The otocinclus catfish will stay at the bottom of the tank and will usually steer clear of any tank mates.  It is considered a peaceful fish mainly because they are so small.  But they are also rather skittish, especially around larger fish.  Therefore, they are excellent swimmers and can be quite a challenge to catch.  They will spend most of their time eating the algae off of something.  Once they have cleared away a part of the tank from algae, then they will move over to another part of the tank.  They are not aggressive at all, but they do get lonely if they are by themselves, so get them in groups of three or more.

Tank Mates for Otocinclus

If you think you will join your otocinclus catfish with some other kinds of fish, then this is where the bigger tank is going to come in handy.  However, you should be careful of what kind of fish you are putting into the tank with your otocinclus catfish.  The catfish are small and peaceful, so do not put any aggressive fish in the tank with them.  Any fish that doesn’t feel that it needs to fight for food would be ideal for the catfish.  Betta fish have an alright relationship as long as there is enough space in the tank.  Betta fish have been known to attack smaller fish, but giving them space will ease their stress.  Shrimp are also good companions with otocinclus catfish.  The best option is to provide many hiding places with your decorative elements.  Goldfish are also fine with otocinclus catfish.   The catfish won’t bother any of these guys, so the other fish leave them alone.  There are many ideal tank mates for the otocinclus catfish such as tetras, boraras, rasboras, barbs, mollies, and other kinds of catfish. 

It is important to remember that otocinclus catfish need to be in groups.  Other tank mates are not good substitutes for other otocinclus catfish.  You can keep just one, but if they do not have a companion, they will get stressed out and health issues may arise.  Suffice it to say, they get lonely.  Therefore, keep an even number between 4-8 fish in a tank. 

Otocinclus Catfish for Sale

If you are looking to buy some otocinclus catfish for your tank, there are your obvious pet shops like Petco and PetSmart.  Most otocinclus catfish will be priced under thirty dollars, but there have been some that have ranged up to $150.  There are many online import stores that are available.  For example, Aqua Imports, Flip Aquatics, and LiveAquaria all sell otocinclus catfish at very reasonable prices.  Just be sure to do your research before you purchase.  There are many different kinds of otocinclus catfish and you might want to be familiar with which one you are getting.

Otocinclus Types

There are many species of Otocinclus, and some are more common than others. Here’s a list of types of Otocinclus.

Otocinclus arnoldi

This type of otocinclus has a lateral trunk coloration composed of a row of 3-6 dark blotches or stripes down its body.  A German aquarist named Johann Paul Arnold first presented it to the British Museum, so the fish was named after him.  Its splotchy, dark design gives it its unique golden look.

Otocinclus batmani

This yellowish version of the otocinclus catfish usually has dark spots on its dorsal fin along with a long dark line down the side of the body.  It almost looks transparent.  The batmani was found in the Amazon Basin in 2006. 

Otocinclus Bororo

 Much like the batmani, the Bororo has a long stripe down the side of its body.  The difference between the two is in the coloring of the body, as the Bororo tends to be a bit more orange than yellow.

Otocinclus caxarari

With a leopard print on the top of its body, the caxarari have a slightly darker look to them.  The prominent design gives them the ability to blend in nicely with the substrate.  This version comes from the Madeira River basin in Bolivia and Brazil.

Otocinclus cocama

Named for the Cocama Indian tribes from Brazil, these cocama fish have more of a zebra printing on them.  They have contrasting colors with one lighter and the other darker, creating a fish that really stands out in a tank.

Otocinclus flexilis

These are another version of the otocinclus that blend in nicely with the substrate.  Their pinkish bodies have spotted dark areas and have a bit of leopard print on the top.  These otocinclus change color with their mood and some of have even become almost black. 

Otocinclus hasemani

This version of otocinclus has an almost transparent body with one dark stripe going straight down the sides.  They have slightly smaller fins and were discovered in 1915 in the Parnaiba River basins.

Otocinclus hoppei

The hoppei have a bit more of a pronounced nose and are often brownish in color with dark spots along its body.  These little guys come from the northern area of Brazil and have been moving throughout South America.

Otocinclus huaorani

Named after the Huaorant people from the upper Napo River in Ecuador, the huaorani have the common dark strip down the side of their body and usually come in black and white coloring with more of a smooth coat of color on the top.

Otocinclus juruenae

Typically found in Brazil, the juruenae has no gap plates on its lateral line, unlike other forms of otocinclus.  It also has a series of three to four diffuse pigment blotches without a distinct midlateral stripe.

Otocinclus macrospilus

One of the most commonly traded versions of the otocinclus is the macrospilus.  The caudal fin marking is the key factor that separates this version from others.  These guys can be very dark with black coloring, but can also change their coloring based on their moods.

Otocinclus mangaba

With an almost ghostlike image, the mangaba has a whitish-gray body with a prominent dark marking just before the dorsal fin. This is one of the more recent versions of the otocinclus, found in 2010. 

Otocinclus mariae

Very similar to the vittatus, the mariae has a thinner and flatter body type with the same distinct dark strip going down the side of the body.  It was discovered in 1940 in in the Rio Mamore region of Bolivia.

Otocinclus mimulus

This version has almost a bluish tone to it as it still has the same lateral stripe.  However, this stripe is more blended into the other splotches of dark on other parts of the body.  It has enlarged odontodes on the dorsal tip.

Otocinclus mura

The mura is a beautiful version of the otocinclus.  It can come in darker colors, but also in a golden body color that brighten up a tank. Its lateral strip has been known to encompass their entire top half of the body.

Otocinclus tapirape

The tapirape comes from Brazil as well and have various sizes of leopard print on the top half of their bodies.  They also have the same lateral strip that is common with otocinclus. 

Otocinclus vestitus

The vestitus has a dark top half and a lighter bottom half.  The pattern on the top of the fish can vary depending on its coloring.  They also have a distinct pattern along the dorsal fin.

Otocinclus vittatus  

Another of the most common type of otocinclus, the vittatus has a slightly prominent eye bulge, as they are known for the big eyes.  They’re also usually darker on top and lighter on the bottom.

Otocinclus xakriaba

This silvery spotted version of the otocinclus can come in grayish silver coloring or orange coloring.  It has a distinct spotted pattern of dark along its body that come in many different sizes. 

Other Types of Otocinclus

There are also other algae eaters that are sometimes confused with otocinclus catfish.  For example, the Siamese algae eater comes from the carp family in Southeast Asia.  Both the otocinclus and the Siamese algae eater love eating algae, but the Siamese algae eaters are just a little better at it.  Their coloring is also quite different from each other. 

There are also the Chinese algae eaters, which are much bigger in size than the otocinclus.  They come in around nine to eleven inches and originated from Thailand and then were moved to China.  The Chinese algae eaters also live a lot longer than the otocinclus.

The corydoras are another that look very similar to the otocinclus in the way that they look and also their size.  However, the corydoras do not really like eating algae.  Plus, the corydoras are a little easier to take care of because they do not require such specific water conditions.

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