Otocinclus Catfish Care Guide

Otocinclus Catfish
Photo by AJC1

The otocinclus, also known as the otocinclus catfish from the Loricariidae family are a species of freshwatercatfish indigenous to South America. They are also referred to as otto fish or ottos fish or with the spelling variation of oto fish. They also have an unofficial name called “dwarf suckers”. This has to do with their sucker-shaped mouths designed for them to feed on algae.

Since they are algae eaters, they are often added to a freshwater aquarium to help clean up the tank. Another amazing thing about the otocinclus is it’s a relatively low maintenance fish. Low maintenance usually equates to easy care and a suitable species for beginner aquarists. Otocinclus catfish like to dwell at the bottom of the aquarium so they are creatures that are easily hidden. Thanks to their markings, they can also easily blend in with the substrate.

Information Chart
Care Level:
Various colors
3-5 years
1-2 inches
Minimum Tank Size:

10 gallons

75-82 ºF, 24-28 ºC
Water Conditions:
Warmer slow flowing water with a neutral pH at about 7
Tank Mate Compatibility
Other peaceful fish

Care Level

As said, the otocinclus catfish is relatively easy to care for. They don’t take too much thought and effort and are great for those just looking to dabble in aquarium keeping. For fish that require less care than a lot of other species, they actually decrease your tank maintenance when added to an aquarium.

Since they are algae eaters, they end up taking care of other fish more than it needs care itself. For them to really thrive, it’s suggested that they are added to stable tank environments where they can get an easy foothold.

Temperament and Behavior

The otocinclus catfish stays closer to the bottom of the tank and keeps out of the way of other tank mates. The catfish otocinclus is considered a very peaceful little fish. Since they are small, they often end up being prey to the larger fish kept in the tank. This contributes to why they are a little bit more skittish than other fish as well.

Due to this, they are excellent runners (or swimmers) and can be very hard to catch. They are algae eaters or tank cleaners, so they spend most of their time on the bottom. When they have cleared that part of the tank from algae, they will migrate to other areas.

These little creatures can also latch on to the side of the tank which is where algae can accumulate as well. When they stick on to the side of the tank, this is when you can get a clear view of their unique markings. Otocinclus catfish also tend to congregate in groups and feed in the same areas.


These cute little catfish are great for smaller tanks. We are talking about 10 gallon small, which is a decent size for most households. It won’t take up too much space and with these little algae eaters that are peaceful and require little maintenance, they are a good addition to almost any setup.

There are many species of otocinclus catfish, with some pretty recently discovered. Since they often fall prey to other fish, the otocinclus sports armored plating across its body.


We keep mentioning that they are small creatures, and now we will give you an idea of just how small they are. How big do otocinclus get? The adult otocinclus catfish grow to only about 2 inches long. They don’t really breathe well which makes them less suitable for swimming for vast distances.


The otocinclus catfish varies in patterns and markings when we look at the different species. We will give you a breakdown of each one and their common markings.

Common and Dwarf Otocinclus

These two resemble each other in terms of appearance. They possess a brown speckled body with a white underside. They both also have a dark stripe running down the length of their bodies with the dwarf otocinclus’s caudal fin being shaped a bit differently.

Golden Otocinclus

Due to their name, the golden otocinclus has more golden hues. If not looked at closely, they can easily be mistaken for a common otocinclus because of the same speckled markings.

Zebra Otocinclus

The zebra otocinclus also takes after its own name, and its namesake – the zebra. You can see black and white stripes along the length of its body and the shape and direction of the stripes can also resemble tiger stripes as well. This is what also earns them the name of Tiger Otos.


These smaller creatures won’t be able to keep you company for as long as you would like and they typically inhabit the tank for 3-5 years. How long they live in captivity is in direct correlation to how they are cared for. If you are able to provide them with the ideal environment, these algae eaters can live for as long as possible.


The otocinclus catfish are a freshwater fish that are considered herbivores. For this reason, you need to make sure whatever food you feed the catfish otocinclus reflects that. Again, they are algae eaters in the wild and are still in captivity. You can look at algae wafers, which make good supplements as well as fresh veggies you have lying around the house.

Lettuce pieces, and spinach are great substitutes for the otocinclus catfish, but make sure you remove any leftover pieces to not soil the water conditions.


The otocinclus catfish, or catfish otocinclus are from the Loricariidae family, and native to South America. They are normally found in freshwater and do well in a freshwater aquarium.

Tank Conditions

They aren’t called “suckers” for nothing. In the wild, they tend to be in slow flowing streams and rivers of fresh water, and in a domestic tank, they adapt by attaching themselves to rocks and substrates. For this reason, it’s a good idea to make sure your tank is populated with suitable plants and other natural inanimate objects.

Since the otocinclus catfish spend most of their time on the bottom of the tank, fine-grained sand is a great substrate to line your tank with. Larger -grained substrates can actually hurt the otocinclus. Rocks and plants are important because that’s where algae abundantly grows. The aquarium needs to be properly decorated with plenty of hiding spaces.


The water temperatures would be best between 75-82 degrees Fahrenheit, which translates to about 24-28 degrees Celcius. You should always keep them in the water temperatures they are used to in the wild. In the aquarium, it’s easier to maintain the ideal tank conditions.

Water Conditions

Warmer slow flowing water with a neutral pH at about 7 is best suited for the otocinclus catfish. It needs to be well oxygenated, so look into that. Also, make sure the tank is placed where there will be plenty of sunlight streaming through the window.

Minimum Tank Size

Since they are small creatures, a small tank will do. These fish like to keep to the bottom and they aren’t big swimmers, which is why a tank size of 10 gallons for a group of 4-6 is ideal.

Should Otocinclus be kept in groups? It is advised that they are, they tend to group together in nature and feed off algae and perhaps algae wafers in certain spots, and there is no reason why they shouldn’t be given that opportunity in captivity.

Remember that the more fish you have, the more gallons you need. Think about increasing the tank size by a few gallons with each fish you add.

Maintenance and Care

Why do my otocinclus keep dying? A lot of people ask that question of these hardy fish. You need to make sure you are taking care of them to the best of your ability. The healthier the aquarium is, the happier your fish will be. They are pretty hardy but can be fragile at the same time.

Adapting to a new environment is the hardest part of caring for the otocinclus catfish, which is why they need to be introduced carefully. The food you feed them needs to reflect their natural diet (consisting mainly of algae and plants), and the aquarium conditions need to be ideal.

Since algae is their main source of food, make sure you don’t completely wipe it out when cleaning your aquarium. The otocinclus catfish is a freshwater fish, and like most other freshwater fish, they are susceptible to sudden water changes. These fish, due to their small size, cannot bear too much movement in the water.

The otocinclus catfish is luckily free of a lot of diseases, but they can develop fungus (not a surprise for most freshwater fish in an aquarium.) The two most important factors are a clean aquarium and healthy food. Once you start noticing a lack of appetite, wounds, color changes and decreased activity, you know your fish isn’t doing so well.

If you happen to have sick fish, make sure you quarantine them away from the rest of the group quickly to prevent the spread of the disease.

Suitable Tank Mates

An aquarium can look quite sparse and empty with only the otocinclus catfish. This is why they are usually supplemental fish in a tank with many others. How many otocinclus catfish should be kept together? We recommend at least 4-6. Just be sure that your tank is large enough. Aside from other otocinclus catfish, what other fish make good friends?


Since they are small and fall prey to other fish, you shouldn’t include any aggressive or predatory species. However, the otocinclus catfish itself can get along quite well with other fish. This is why there is a myriad of choices for roommates such as tetras, barbs, mollies, other catfish, and even other algae eaters such as shrimp and snails.


The otocinclus catfish is not easily bred in captivity, and this is due to their particular needs. The conditions such as the water temperature and things like lighting will also affect your chances. The water should be kept at warmer temperatures anyway (with it being on the warmer side for breeding) so the water condition is the least of your worries.

You know breeding is about to happen when the males start chasing the ladies around the aquarium. The female otocinclus catfish lay eggs around the surface of the tank in small bunches and the males head over to fertilize them. The incubation period of the otocinclus catfish only takes a few days. After that time, you will have plenty of fry swimming around and increasing the population of your tank.

The babies need healthy food as well and algae as well as bacteria are the main source of food. The care level needed for the fry is minimal and they will soon start looking and eating the same food as the adults.


The otocinclus catfish are handy little pets to keep around. They are on the smaller size compared to other catfish and like to swell at the bottom of the tank. However, much like most other catfish species, the otocinlus catfish is quite a peaceful fish and can get along well with other tank mates. Not to mention their handy role at keeping the aquarium clean. They can save you the trouble of feeding them regularly as well with the natural buildup of algae in the tank.

3 thoughts on “Otocinclus Catfish Care Guide”

  1. Otocinclus, I purchased 6 recently, 3 at a time. Put them in my established tank and also put agar wafers in. All of them have died!. I only have small tetra fish in my tank so they are not eating them. I do 60 minute acclimation when I bring them home. My Nitrates are only 5 to 10 ppm. They look good for 4 or 5 days then die. Frustrating cause I really like that fish!

  2. Very hard fish to keep the Oct cat nitrates really need to be at 0 at all times, which I found impossible to do with planted aquarium as the Ferts for my plants had nitrate in the bottle . So I could never get my lower than 10 ppm, so I just went out and brought Siamese algae eater instead .

  3. Hi, My otocinclus (I have 2) have bred!! I thought what I vacuumed out what I thought were infertile goldfish eggs. I use old water from tank cleaning to add nutrients for my aquatic plant clippings I’m growing in another container look in when I saw something move and behold itty bitty oto. What do I do they are in separate place but do I just let it feed on algae when can I move back in Help me


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