Otocinclus stats infographicOtocinclus, also known as dwarf suckers, or otos, are algae-eating, reclusive catfish species.

They are a peaceful, low-maintenance, and perfect addition to a community aquarium. However, these dark striped fish pop a lot, which increases the nitrate level in the tank.

In this article, you get to learn about this diligent alga cleaner, its feeding and living needs, and how to elongate its life span.

Otocinclus Stats

Otocinclus stats contains the quick stat and the classification stat.

Quick stats:

Otocinclus size 1.5 inches or 4 cm
Tank size( minimum) 16 inches
Strata Bottom to middle
PH 5.2 to 7.5
Hardness Soft to hard
PH 4.0 to 20.0
Otocinclus Life span Up to five years

Classification stats:

Order Siluriformes
Family Loricariidae
Sub-family Hypoptopomatinae
Genera Otocinclus
Species Varies


– Names

Other common names for Otocinclus are Otos and Dwarf suckers.

– Origin

The Otocinclus catfish are originally from the small freshwater rivers in South America, Venezuela, and Argentina.

– General Body Form

The dwarf sucker looks similar to the common otos species. They are a nano-sized breed of catfish that hardly outgrow their two-inch size; some adult otos are no more than an inch. They are shaped like a narrow cylinder with a smaller width around their head and caudal fin. The females are rounder and bigger than the male.

Otocinclus also known as dwarf suckers or otosAn Otocinclus has a big mouth which they use to clear off algae growing in the aquarium walls. It has brown-colored stripes parallel on its body but fades off at the fins region. It has a dark dot on its tail with armor-like protective body plating. The protective covering shields them from aggressive tank mates or harsh surfaces on the aquarium substrate or other parts.

Their elongated body is slightly curved at the back with eyes that seem to be on the sides, but you can see it when you look at them from under their bodies. The mouth looks like it’s turning downwards and possesses transparent fins but no adipose or barbels fins.

The otos have a deep greyish-green distinct body color, a dark back but a white belly with a yellowish hue. They breathe through a hole between their esophagus and stomach, unlike other fish that use gills. It limits their ability to take in the air.

– Behavior

The dwarf suckers are algae eaters; they help hobbyists clean and improve their aquarium water conditions. Unlike other catfish species, otos enjoy smaller water bodies like minor rivers. Aquarists call these dwarf suckers “beginner-friendly” since you do not have to spend a lot of time taking care of them.

They are diligent and effective; they add variety to your aquarium and reduce your effort by controlling algae growth. They are problem-free and adaptable to a wide range of water conditions. They are bottom strata dwellers that endeavor to stay out of the other species’ way.

Because of their minute size, they scare easily and are often prey to bigger fish. Otos are a docile breed and would join a school to remain safe in their natural habitat or aquarium. The Otocinclus are more social in huge groups and somewhat uncomfortable with smaller schools. Still, they are active when alone in a tank.

– Coping Mechanism

The otos would sometimes imitate the corydoras (they have spikes that contain venom) to protect themselves. They are more active during the day than at night, but they can turn nocturnal in a community tank with larger aggressive fish. They are timid but fast swimmers.

– Otocinclus lifespan

An aquarium-raised Otocinclus can live up to five years, depending on its feeding, care, and water conditions.

Otocinclus Care

The recommended Otocinclus care is relatively low-maintenance rather; they assist you. It makes them very attractive to the hobbyist who desires healthy fish but with little effort. They give a lot of benefits than other freshwater fish.

Dissimilar to other small fish species with special needs, they quickly adjust, but you have to be observant.

1. Tank Condition

The otos are often found by enthusiastic aquarists attaching their mouths to algae-covered rocks and surfaces in the wild. So you have to simulate it in your tank by adding lots of surfaces like rocks, wood, etc.

If algae don’t grow naturally, you have to trigger the growth because the otos catfish enjoy them. Instead of a gravel substrate, opt for a grainy or sandy substrate to prevent injuries as they inhabit the tank’s bottom.

Even if they have a protective covering on their body, you should remember, an intense scratch can lead to more significant concerns like infections. Add in items that the otos can use as a shelter when it is stressed when larger tank mates chase them or are tired.

Plants are necessary to shield these reclusive Otocinclus from everything; they are skittish naturally. They require lights; natural light is good, but you can use LED and strategically place plants to form a shade.

2. Tank Cleaning

Otocinclus are nitrate sensitive. If you test the aquarium water and notice it, you need to run an immediate water change. However, you can use nitrate pads to regulate it. If you see high levels of nitrates, take out some fish from the community tank.

3. Water Parameters

They are freshwater catfish from slow-moving small water bodies. You should change their tank water weekly to maintain the water quality. They thrive in a tepid water temperature range of (68 to 82)°F with a PH range of 5.2 to 7.5. However, the water has to be soft with a reading of 4.0- 20.0.

Regular water changes would eliminate the ammonia and nitrates in the water. Your Otocinclus pet fish would flourish in water containing oxygen. Still, you can use a regular tank pump and nitrate filtration system.

4. Tank Size

The Otocinclus tank size should be at least a 10-gallon capacity aquarium. It would be enough space for six co-specific otos fish. If the aquarium is too large, the otos get uncomfortable. They like to see members of their school easily and around them, or they would be terrified. However, smaller tanks can not produce the correct quantity of algae nutrition that they need.


Otocinclus fishThe Otocinclus breeding is one reason aquarists can consider it a hardy fish. The rigorous process is difficult for a tank-raised catfish.

– Clean The Tank

They are incredibly picky and particular about their needs during breeding. They expect the simulated environment to be almost identical to their natural habitat. When you decide to breed your otos, perform a water chang e and clean the aquarium. It is wise to put a group of co-specifics in the tank to find a mate naturally.

– Pair Them Up

To do this, you have to identify the male and female Otonciclus catfish because if you only put in males, breeding would never happen. This is because the otos exhibit sexual dimorphism; the males are slim and smaller than the female when they are ready for mating. Also, the male has a genital papilla; it looks like a nipple-looking growth at its tail’s lower region.

– Feeding And Mating Triggers

Feed the otos catfish with healthy, nutritious meals frequently as you prepare them for breeding. Increase the water temperature but not above 79°F as warmer conditions can trigger spawning. Mating takes a toll on the otos, male and female; the chasing could go on for hours.

– Breeding Process

When the freshwater nano fish are ready, the male otos initiate the mating by chasing their mate around for a while. Then he tried to connect with her in the form of a “T” posture. The oviparous female then lays her eggs on different flat surfaces in the aquarium while the male fertilizes them. Thus, the good eggs look clear with a murky inside, while the bad ones would look solid white.

Observe and separate them as the spoilt eggs will not hatch and are infected. The process continues sporadically until the female releases all her eggs. Breeding in other fish species is slightly different from this catfish breed. The male doesn’t develop any aggressive instinct to guard the eggs. Instead, the Otocinclus male considers his job finished after fertilizing them.

– After Breeding

It is ideal to use a separate breeding tank to ensure other fish do not eat the eggs or fry. After a few days, the eggs hatch, and the fry would begin to swim in the tank. The otos young eat algae and bacteria initially and later progress to adult meals.

Tank Mates

There are three significant ways to pick an Otocinclus tank mate;

  1. Water conditions: the tank mate has to be a freshwater fish and requires the same range of water temperature, PH, and hardness level. If you put in the wrong parameters, you can endanger the otos or its tank mate. Do not try to manipulate the Otocinclus temperature range to favor the different breeds. They can get an infection, fall severely sick, or even die.
  2. Temperament: the Otocinclus are known as shy and skittish fish yet sociable. They are a very peaceful breed; you should pair them with fish with a similar temperament. For example, an aggressive tank mate would constantly try to harass and bully the otos. Some fish are hostile about their mate or protecting their young, while others are temperamental about food and territory. If you can decide which behavioral trait is the problem and strike a balance, it would make it easier to choose a good tank. For example, if the tank mate is aggressive about their young, transfer them to a breeding tank.
  3. Size: the tank mate size is significant. Bigger fish see smaller ones as a food source and would most likely eat them. The Otocinclus would be uncomfortable in a tank with a large fish. Fish with largemouths are a terrible choice as they would eat the otos in one bite.

Here are some ideal otos tank mates.

  • Co-specifics: the otos behave similarly. They thrive better in bigger groups but would cope in small groups.
  • The corydoras: these catfish are an excellent option for the Otocinclus because they have similar behavioral traits. It is as shy as the otos yet social among the right-sized fish. They are also energetic and are bottom strata breed.
  • Invertebrates like shrimps and snails: the bamboo shrimps are ideal because they are innocuous. Apart from not having any sharp body parts for defending themselves, they are also not hostile like the otos. Snails like rabbit snails, Malaysian trumpet snails, gold Inca snails, ivory snails, Japanese trapdoor snails, Ramshorn snails, and mystery snails are all excellent tank mates for the Otocinclus. Other shrimps are red cherry shrimp, Amano shrimp, vampire shrimp, and ghost shrimps. Be sure the algae in the tank is sufficient for all the tank mates.

Other fish to consider are mollies, cherry barbs, Harlequin Rasbora, tetras, guppies, dwarf Gourami, angelfish, Danios Zebra Loaches.

Some fish do not go well together; in this case, the Otocinclus can not share a tank with the following species. Cichlids are a red flag because they would exhaust the otos with aggression and bullying. Others are goldfish, Jack Dempsey striped convict, Oscar, and texas.

  • Crabs: unlike the shrimps, the crabs would try to grab the Otocinclus and attempt to eat them. Also, crayfish are not ideal tank mates. There are a lot of options not to try for the benefit of your pet fish. Search out the potential tank mates’ various behavioral traits and their compatibility with the Otocinclus catfish.

Proper Diet

The otocinclus fishThe Otocinclus diet is primarily an herbivorous one. However, in smaller groups, they get so conscious of danger and spend so much time dodging and hiding without eating correctly. The herbivores’ diet consists of vegetarian meal plans like algae; they regularly eat this in their tanks. Nonetheless, it would help if you still feed your pet fish with other nutritious meals.

They also eat aquarium plants and chemical-free vegetables like; cucumber, lettuce, salt-free peas, zucchini, and spinach. Vegetables are good substitute meals, but algae are more nutritious. Algae wafers are also an alternative to fresh tank algae, mainly when the formation is slower than their grazing ability. Otos also eat biofilm from tank surfaces and catfish pellets.

The leaves on plants enhance biofilm growth. Plants like cryptocorynes, Anubias, and java Ferns are good plants to grow in your Otocinclus tank. Cut up their food, cook them for some seconds and soak them in cold water. Afterward, put them into your pet’s aquarium and check that it gets to the bottom of the tank.

If they do not eat all their meal, perform a water change or scope out the food item before it begins to decay. Feeding Otocinclus too much food is unhealthy and wasteful; give them balanced regular meals.

Common Feeding Issues

The Otocinclus can be attached to eating only algae and refuse to eat an alternative. They do this not to be spiteful or hardy fish, but it’s just their nature. They probably do not understand that other food items are safe to ingest apart from algae. So they would not take your vegetable suggestions or wafers and would rather starve.

If you worry about such pet fish, here is what you can do, grow your supply of algae. Yes, it is possible and effective.

The types of algae the Otocinclus likes are green dust algae, diatoms/brown algae, and green algae. Types of algae the Otocinclus would not eat; staghorn algae, black beard algae, and hair algae.

Steps involved in growing algae are:

– Step 1

Get a sizeable transparent container; you can use an empty aquarium.

– Step 2

Put some water in the tank.

– Step 3

Put tank accessories like rocks, wood, ceramic filter, or marble chips. All the accessories should be safe and clean.

– Step 4

Turn on the aquarium lights and set it to the brightness and highest intensity for a week.

– Step 5

Apply fertilizers on the aquarium plants to help them grow.

– Step 6

Use an air stone; it would cause algae growth in the tank by making the water oxygenated.

– Step 7

After some days, you would observe that the accessories are turning green, remove them, and put them in the Otocinclus tank for it to eat.

– Step 8

Repeat the process to grow some more algae.


  • Otocinclus catfishThe Otocinclus are social, but they scare easily.
  • They are not aggressive.
  • They get along with the corydoras breed.
  • They are vegetarians but would occasionally eat live meals.
  • They are picky about their mates.
  • Their breeding is a bit challenging to perform, particularly for beginners.
  • They hardly grow more than a 2inch size.
  • The otos are avid algae eaters.

When the Otocinclus catfish eat the tanks’ algae, you do not get to worry about feeding them frequently or deep cleaning your aquarium. Still, get these low-maintenance catfish pets to acquire a free clean-up crew up as well.

5/5 - (17 votes)


Please enter your comment!
Please enter your name here