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Otocinclus Catfish- The Easiest Cleaner Fish You Can Raise

If you’ve ever considered raising an algae eater, you may have considered the Otocinclus catfish. These creatures are some of the best algae eaters around, and they are one of the most common catfish species you can raise. These gorgeous pieces are easy to care for and are a popular choice for beginners.

But not so fast! Before you start picking out names for your Otocinclus, you better make sure you are prepared to raise one successfully in your freshwater aquarium. There’s fish are popular for a reason – they are super easy to care for. However, these are some basics that you need to know before you decide to bring an Otocinclus home to your fish tank today.

Ready to get started? Here’s everything you need to know.

Otocinclus Catfish

Otocinclus Background

Otocinclus Catfish

Otocinclus refers to a genus of freshwater catfish. Belonging to the family known as Loricariidae, the name Otocinclus actually refers to about 19 different species of fish. They come in all kinds of sizes, colors, shapes, and patterns, and are often referred to as dwarf suckers or even simply as Otos.

These fish are all native to the continent of South America. They tend to be found most often in the rivers of Venezuela and North Argentina. They are not found in the Amazon River, which is bizarre for tropical fish that are native to South America.

Otocinclus catfish are generally found in the shallow rivers and small streams of South America. They prefer waters that are slow-moving so that they can attach himself to the river bottom or the rocks as they search hungrily for algae.

The waters to which these fish are native tend to be well-oxygenated. Therefore, the pH is usually neutral. The substrate is typically soft and sandy and contains plenty of debris like driftwood, rocks, and plants. That being said, there aren’t usually a ton of plants in this fish’s native habitat – this is because the Otocinclus prefers to have access to lots of light

These fish are popular aquarium species not only for the way they look, but because they are worker fish – they will easily remove most of the algae in your tank therefore if you find that the algae in your tank is getting out of hand, you might want to consider purchasing an Otocinclus. Not only will they eat up most of the algae, but they’re also a great fish species for beginners. They don’t take a lot of time to raise and they are also fun to watch.

As bottom dwellers, you shouldn’t struggle to find this popular algae-eating species in stores. They are found in most aquarium and pet stores, and you can generally purchase one for just a few dollars. The price tends to vary depending on the age, size, and species of the fish.

Otocinclus Appearance And Behavior


Otocinclus catfish are great species for tiny ten-gallon aquariums because they are very small – even the largest adults rarely exceed 2 inches. These smallest species of Otocinclus only grows to around an inch in length, while the largest reaches only 2.2 inches long.

These fish are simply built, lacking a lot of glitz and glamor. They have bodies that are small and cylindrical. These narrow toward the caudal fin and heads. They have strong mouths that they use to latch on to the algae-covered surfaces in your tank.

These fish are different than many other types of catfish because they have rigid rows of strong armor plating. This armor plating protects the Otos from aggressive, predatory fish and harsh substrates.

Otos can breathe air to some extent. They have a unique duct that is situated between their stomach and esophagus that allow them to breathe in small amounts of air.

You can tell males and females of this catfish apart, but this can be somewhat difficult to do. Females are slightly larger and more broad, which you may be able to see better when you are looking down at your fish from the top of the tank. However, there aren’t many differences besides that.

There are several types of Oto catfish, and we will outline the major differences among the top species here.

The Common Otocinclus, or otocinclus vittatus, is found most commonly in South America. It has the widest distribution and is a speckled brown color. Its belly is white and it has a brown stripe running from its head to its caudal fin. Its other fins are practically transparent.

The Golden Oto, on the other hand, despite looking a lot like eh Common Otocinclus has brown colors that are closer in shade to gold. The Zebra Otocinclus, or Otocinclus Cocama, looks – as you might expect – a lot like a zebra. It has black and white stripes that run vertically across its body. It has horizontal stripes along the head. Interestingly, the stripes of some individuals don’t run as straight, so this fish is often nicknamed the Tiger Oto, too.


The Dwarf Oto is another common species. To be fair, it looks a lot like the Common Otocinclus. It can be differentiated because it has a caudal fin with a unique design. The lateral stripe becomes paler just before it reaches the caudal fin. The tail, too, is different, possessing a large batch of color.

Finally, Silver Otos, or Otocinclus vestitus, looks much like other species of Otocinclus. In fact, it has the same lateral stripe. However, its brown colors are a lot closer to silver, as you might expect, by the name of this fish.

If you have an Oto, you may realize that you rarely see it! These peaceful, tiny fish try to stay well out of the way, and are incredibly skittish and shy. If you have larger fish in your tank, you will need to keep an eye on them because they have a tendency to go after the smaller Oto catfish.

In fact, the only time you will likely see your Oto is ween it is darting across the fish tank in fear! These fish can move quite quickly, and if you’re trying, for whatever reason, to catch one in a net, you are likely going to have a hard time doing it.

Instead, these fish prefer to spend most of their days hanging out at the bottom of the tank. They will also chill on the surfaces of the plants, walls, and decorations in your tank. They will spend their time in voracious pursuit of algae, and if there’s no algae where they currently are, they’ll happily move on to the next available surface.

These fish aren’t schooling fish, but they tend to stick together, preferring to graze in the same general vicinity as the others. They are quite interesting to watch, as you can often get an interesting look at how they use their mouths to grip the side of the tank.

Otocinclus Tank Requirements


Setting up your Oto’s tank should be relatively easy. Since many popular aquarium fish are native to South America, these fish will require similar conditions and will get along well in most kinds of tanks.

Otos are bottom-dwelling fish, so it’s important that you spend a lot of time considering how the bottom of your tank is designed. Make sure you use a sandy substrate or one that is otherwise fine-grained. A coarse-grained substrate will scratch the body of your fish and lead to serious illnesses. While these fish are a bit more resilient to bodily damage than other types of catfish, you do still need to pay attention to the type of substrate that you are using.

It’s a good idea to fill your tank with plenty of decorations. The best option is to use rocks as caves, as these will be used by your Otos as shelter when they are stressed or being threatened by other fish in the bank. You can also use live plants, like Staurogyne repens, which will provide additional shelter.

Plants are a good addition to an Oto tank for another reason, too. They provide additional surfaces and oxygen to facilitate the growth of algae in your tank. Your Oto won’t eat your live plants, either – he will stick to it and remove the algae that has grown on the plant with his powerful mouth.

Although your Oto will eat a large amount of algae in your tank, you shouldn’t put all the work on him. You still need to clean your tank from time to time to make sure that ammonia and nitrite levels are low. These should be at 0 ppm at all times. Conduct a water change every week or other week, which will help remove toxins and keep your tank a healthier place to be.

The temperature of your tank should remain stable and consistent between 72 and 79 degrees Fahrenheit. The pH should be as close to neutral as you can get – ideally between 6.8 and 7.5. You should try to use soft water, preferably water than has a rating that is not higher than 15 dH.

You don’t need any special requirements when it comes to filtration and oxygenation. You can install a small filter and a standard air pump to improve oxidation, but the latter is definitely not necessary. You can also install standard aquarium lights, which will provide your Oto with the exact amount of light he needs to stay healthy.

Otocinclus are small fish thrive in small tanks. You can use a ten gallon tank for up to six Otocinclus. If you add more than that, you will want to add a few gallons per fish. The wider the tank, the better – this will provide your fish with more surface area on which to find algae.

What Do Otocinclus Eat?


Otocinclus catfish are herbivores – this makes it a bit more difficult to find appropriate foods for them. While they normally eat algae in the wild – and will also prefer to eat this in your tank – you might need to add some other foods, too. Naturally occurring algae in the tank can run out quickly if you have a large group of Otos.

You can purchase algae wafers from the store. These can be added every couple of days and will disappear in just a few hours. You can also feed your Oto fish food from around the house. Some good options include finely diced green vegetables, like spinach, lettuce, or zucchini. You can cut off a small piece and drop it into the tank a few times a week.

Monitor your Otocinclus carefully. If you notice that food remains in the tank 24 hours after feeding, make sure you remove it. This will reduce the amount of waste that builds up in your tank. If you want to be really creative, you might even try feeding your Oto some homemade DIY fish food!

Avoid overfeeding your Otocinclus, as this can cause health problems. You will also want to keep an eye on the algae levels in your tank.

Otocinclus Tank Mates



Otos are peaceful species and won’t cause problems for any of your other fish. There are thousands of tank mates for you to choose from, but you do need to keep in mind that although these fish are not troublemakers themselves, they can become prey for aggressive or large fish.

Avoid keeping your Oto fish with cichlids, who will easily hunt down and kill your Otocinclus catfish. Any fish that have mouths big enough to eat a whole Otocinclus should be avoided.

That being said, you still have lots of options. You might want to consider species such as Danios, Corydoras Catfish, Dwarf Gourami, Mollies, Zebra Loaches, Tetras, Harlequin Rasboras, Cherry Barbs, Angelfish, or Guppies. Invertebrates are also a good choice- shrimp and snails have unique behaviors and appearances, and you don’t have to worry about them harassing your Oto fish – or vice versa.

Remember, you can always keep Otocinclus catfish in groups of their own kind, too. In fact, you should try to keep these social fish in groups of four to help them keep themselves entertained.

Common Otocinclus Diseases


If you are able to maintain a healthy tank environment, you will likely be able to raise a healthy Otocinclus. However, they can be fragile in some cases, so you should be vigilant for signs of disease. Make sure you quarantine any new additions to the tank, and watch them carefully for the first few weeks. They can sometimes be vulnerable to movement and can die after you introduce them to the new tank.

Algae is a common problem in the Oto tank. Many people assume that if they have Oto catfish, they won’t need to ever clean their tank. This is not true. Make sure you clean the tank regularly and keep an eye on the parameters of the water. Watch out for levels of ammonia, pH, temperature, nitrates, and nitrates that are not right.

You will be able to notice most signs of illness in your fish right away. The most common disease to affect freshwaterfish is ich. Also known as white spot disease, this disease causes an increased rate of respiration, loss of appetite, and complete inactivity.

Other signs of potential disease in your tank include a lack of energy, color changes, wounds, and obvious blemishes. General discoloration can also be a sign of problems.

While an unclean tank is the most common culprit behind typical fish disease, you may also have a fish population that becomes ill because of what you are feeding it. If you are not feeding your fish something that is found in its natural diet, stop feeding that food immediately. Similarly, switching up the diet during at time of illness can be enough to encourage the fish to feel better. That being said, if you change your fish’s diet too abruptly, it can cause stress that influences disease.

As always, if you notice that a fish has fallen ill, you should quarantine it and isolate it away from the other fish. This will not only help the sick fish to recover more quickly, but it will also protect the rest of your fish from any danger.

Breeding And Life Spans Of Otocinclus

As a fishkeeper, there’s not much that you need to do to lengthen the lifespan of your Otocinclus catfish. You just need to make sure that you provide them with the conditions we detailed above. When given the proper living conditions, these fish can live for three to five years in captivity.

Oto catfish are also remarkably easy to breed in captivity. Though not as easy to breed as other species of fish, if you are lucky enough to get the perfect combination of breeders in your tank, this is something that can easily be done.

You will need to make sure conditions are optimal. Your tank should be clean and your Otocinclus fish should be fed a varied, nutritious diet. You can raise the temperature slightly to encourage spawning, but you shouldn’t go too far about 79 degrees. Rising temperatures in the wild usually indicate that it’s time to mate.

When your fish are ready to mate, you will notice the males pursuing females, chasing them around the tank. Once the females and males are both ready, the male will fertilize the eggs of the female. She will lay these ins mall bunches on surfaces within the tank.

In just a few days, your fry will be swimming about. They usually will feed on the bacteria and algae that are already in the tank – you don’t need to feed them any special kind of food. It doesn’t take long until the young fry can eat the same foods as their parents and other adults in the tank.

Is An Otocinclus For You?

If you struggle to keep your fish tank free from algae and you already have a small freshwater tank with some other fish, the Otocinclus is a great addition. It is a peaceful community fish that gets along well with practically any other type of fish and it’s hard to make a mistake that will seriously mess up your prospects when you are raising this delightful species.

If you end up purchasing some Otocinclus catfish, you will be rewarded with a new clean tank and a social group of fish – just remember to feed them some algae wafers every now and then, and you’ll be good to go!

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