Dwarf Otocinclus: Tired of Plecos and Corys? Try the Dwarf Sucker!


Dwarf Otocinclus: Tired of Plecos and Corys? Try the Dwarf Sucker!

Want to mix things up with an adorable, low-maintenance, and efficient algae eater? I know Plecostomus and many other Algae Eaters often do a fine job. But once they pass 12 inches they can be a real hassle for aquarists with a smaller tank.

Fortunately, there is an algae eater option for aquarists who prefer small tanks and small fish. Introducing The Dwarf Otocinclus! Not only are they a breeze to care for, but their peaceful demeanor makes them the perfect addition to any planted tank.

And the best part? They have a talent for keeping your tank sparkling clean and your plants well-groomed.

I’ll be sharing all the info you need to keep your Otocinclus Catfish thriving.

Otocinclus (1)

Overview of Otocinclus Catfish

The Dwarf Otocinclus (Otocinclus Affinis), also known as Otos or Dwarf Suckers, are peaceful, even shy in character, especially if you only have one or two.

They’re the perfect sidekick to keep your aquarium’s plants healthy, and they won’t disturb any of your other fish.

These catfish are tough. They can adapt to a variety of water conditions and they’re not picky eaters. Whether you’re new to the hobby or a seasoned aquarist, Otocinclus catfish are a reliable and low-maintenance addition to your planted tank.

Typical Otocinclus Behavior

These little ninja cats are like superheroes of the aquarium world. They stealthily swim around and suck up any algae in their path. They’ll keep your tank clean, and you won’t have to worry about scrubbing it down as often.

In nature, they form vast schools of hundreds of fish, which makes them much more outgoing when kept in groups. They often ignore or avoid all tank mates in their quest for soft green algae.

This makes them ideal tank mates for nano and small fish communities.

Otocinclus Catfish Appearance

Dwarf Otocinclus are cute but not exactly colorful. They have a dull grey back with a creamy white belly.

A black stripe runs the length of their flank from tail to the tip of their conical noses. And like their cousins the Plecostomus they have a compressed body with a downturned mouth that helps them attach to hard surfaces.

Otocinclus also have fins reinforced by sharp spines – so be careful when handling them as these spines can easily get caught in a net.


How Long Do Otocinclus Catfish Live?

Dwarf Otocinclus are slightly longer lived than Guppies and other fish. 3 to 5 years when well cared for is an average lifespan for Otos, with occasional reports of up to 7 years.

A wholly vegetarian diet, warm water, and the company of their own kind improves their lifespan.

It’s important to note that Otocinclus catfish are sensitive to water changes, so it’s crucial to maintain consistent water parameters to ensure their well-being. Regular water changes, a balanced diet, and avoiding overstocking the tank setup are key to keeping Otos healthy and prolonging your Otocinclus lifespan.

How Big Do Otocinclus Catfish Get?

As you’d expect with that name, Dwarf Otocinclus stay very small. 1-2 inches is standard, with females reaching up to 2 inches on occasion. Their small size makes keeping a group of them easy even in small aquariums.

While 5 gallons is an absolute minimum, 10 gallons or more allows for algae and biofilm to accumulate, which they prefer eating above everything else.


Sexing Otocinclus Catfish

Sexing Dwarf Otocinclus is one of the only real challenges in keeping them.

The males and females look almost identical in all respects, from color to size. Females are often (but not always) slightly longer and noticeably broader than males as their ovaries take up extra space in their body cavity. In addition, males are generally smaller in size compared to females.

The best way to accurately sex Otocinclus catfish is to examine a group of fish that are all of similar age. This allows for a better comparison of size and fin shape.

It’s worth noting that the sexual dimorphism in Otocinclus catfish is not very pronounced.

When ready to breed their bellies take on a yellowish hue from the developing eggs. You can also tell due to the behavior of the males, who will spend time chasing the females about, hoping to breed when she’s ready.

Therefore, proper observation and patience is key when attempting to sex these fish.

Optimal Water Conditions for Otocinclus Catfish

As tropical, equatorial fish from the Amazon basin, Dwarf Otocinclus should be kept in warm, stable condition where the temperature rarely gets below 72℉. And if you’re looking to breed them, temperatures above 82℉ are essential, alongside the right water chemistry and aquascaping!

In order to provide a suitable habitat for Otocinclus catfish in captivity, it is important to mimic their natural water conditions as closely as possible.

Water Chemistry

Most Amazonian fish prefer soft, acidic conditions and Dwarf Otocinclus are no different. They are quite adaptable and will thrive even in slightly alkaline conditions up to pH 7.5. But neutral to acidic (5.5-7.0) is what Otos prefer.

Here are the conditions they are typically found in!

These algae and plant rich conditions are full of decaying wood, leaves, and plants that release tannins into the environment. Tannins help buffer the water towards acidity. And the mineral poor soils of the region ensure that rainwater remains soft (mineral-poor).

These conditions are harder to get when using tap water, which is typically alkaline and mineral-rich. But if you’re looking to help them thrive and breed, soft, acidic water is a major element!

To maintain good water quality, it is recommended to perform a weekly water change of around 10%-15% is recommended.

Dwarf Otocinclus aren’t especially sensitive to ammonia and other pollutants but you should still keep a careful eye on the concentrations and do water changes as needed if you see levels increase.

Tank Size Setup for Otocinclus Catfish Care

Being small enough to qualify as nano fish, Dwarf Otocinclus need next to no aquarium space. A minimum of 10 gallon tank size is great if you want a trio to act as algae eaters for a betta or a group of tetras.

It is also important to provide plenty of hiding spots and hiding places in the form of plants, driftwood, or caves. Otocinclus catfish are natural algae cleaners and require a well-established aquarium with a sufficient amount of algae growth to feed on.

But 15-20 gallon tank size is a better choice as they are less likely to run out of algae and biofilm to munch on. You can also keep a few more, helping them feel more comfortable and increasing the chances of spawning.

Here’s a beautiful tank sized:

Tank Decorations

When decorating a tank for Zebra Otocinclus, it’s important to consider their natural habitat and behavior. These small catfish are native to South American rivers and streams, where they live among driftwood, rocks, and vegetation.

Plants also create shade and aerate your substrate through the actions of their roots. Thickly tangled live plants are also where Dwarf Otocinclus prefer to deposit their eggs.

Nearly all plants are appreciated by them, but if you’re looking for choices that love heat and are great for collecting Dwarf Oto eggs, you can try any of the following:

  • Java Fern (Microsorum pteropus)
  • Java Moss (Vesicularia dubyana)
  • Amazon Sword Plant (Echinodorus sp.)
  • Cryptocoryne (Cryptocoryne sp.)
  • Hygrophila (Hygrophila sp.)
  • Guppy Grass (Naja guadalupensis)

Compatible Tank Mates for Dwarf Otocinclus

Zebra Otocinclus are some of the best freshwater aquarium fish in the hobby. They are peaceful, sociable, and being vegetarians they won’t bother even the tiniest of fish fry or eggs.

Just make sure that you match them with other fish that have a similar temperament since these tiny catfish species are easily bullied.

Nano fish are by far the best choices (fish under 1 inch), as Dwarf Otocinclus are timid and can be easily stressed by aggressive tank mates.

These include phoenix rasboras, pea pufferfish, bumblebee gobies, and the like. But smaller community fish (3 inches and under) can also work well. Dwarf gouramis, bettasneon tetras, platies, mollies, and guppies are popular choices.

Bottom dwellers can also work so long as they are equally peaceful, like corydoras and rubber plecos. Larger fish – Plecos can be on the aggressive side, as can other large catfish species.

Good tank mates for Dwarf Otocinclus are:

  • A school of Tiger Barbs, Bettas, Neon Tetras, Platies, Guppies, and other small Community Fish
  • Chili Rasboras, Bumblebee Gobies, Pea Pufferfish, and other Nano Fish
  • Corydoras and other peaceful bottom dwellers
  • Other Dwarf Otocinclus

Worst Tank Mates for Algae Eaters?

WARNING: Choosing the wrong tank mates for algae eaters can lead to a disaster in your aquarium. Dwarf Suckers, such as Siamese Algae Eaters, require a peaceful and calm environment to thrive. Aggressive fish, such as Cichlids, can stress out and harm your algae eater. Similarly, larger fish, such as Oscars, can mistake a Oto Catfish as food and attack them. It’s essential to research and carefully choose the right freshwater fish to ensure the safety and well-being of your algae eaters.


Otocinclus Catfish Diet

Dwarf Otocinclus are completely vegetarian fish. They not only don’t need but will entirely ignore brine shrimp, bloodworms, and other animal-based foods that other tropical fish love.

Instead they hunt for green algae – both hair and creeping types – that grow on plants, rocks, and the surface of your aquarium glass.

What to Feed Otocinclus Catfish?

They are very plant-friendly, however, and won’t eat even the softest of plants, such as Anacharis and Cabomba. This makes Dwarf Otocinclus ideal algae eaters for most planted aquariums.

Their small size allows them to thoroughly clean even fine leaved plants where large Oto Cat may not do such a great job.

The common Oto Catfish loves to eat algae, but it isn’t always a reliable source of food unless your water is nutrient rich and you have plenty of light. And even then enough Otocinclus may reduce or eliminate it entirely, making supplemental feeding necessary.

Vegetable-based foods are what you want to provide, including spirulina-enriched algae wafers and lightly blanched terrestrial vegetables. Zucchini, lettuce, spinach, and other veggies, lightly boiled, are excellent when clipped and left in place for a few hours.

You can also buy Japanese nori, a dried seaweed used in sushi and marine fish food. A few strips, once soaked in water and clipped in place, are an ideal food source for Dwarf Otocinclus!


How Often Should I Feed My Dwarf Otocinclus?

Dwarf Otocinclus aren’t like most fish; you can go long stretches without needing to feed them if your aquarium grows abundant green algae.

But once you run out you’ll need to provide a ready source of vegetables because these fish feed continually. They are grazers, like little aquatic cows, rather than eat and relax feeders.

But if you drop in an algae wafer or three or clip some vegetables in place, a single feeding per day is plenty for a group of Dwarf Otocinclus!

Breeding Otocinclus Catfish

It’s time to add some excitement to your aquarium game!

Breeding this freshwater catfish is a blast and I’m here to tell you all about it. These little fish are peaceful powerhouses and they’ll liven up any tank in no time.

But let’s make sure we give them the love and care they deserve, after all, it’s not just about having fun, it’s about doing it the right way.

Let’s make some tiny fish babies and bring some life to your freshwater tank!


How Do I Condition Otocinclus Catfish to Spawn?

Water conditions and thick plant matter are the two most important things you can provide to help condition your Dwarf Otocinclus to spawn.

Octocinclus catfish prefer soft, acidic water conditions in order to breed. The dGH (General hardness) should be at or below 2 degrees, meaning you’ll need a source of demineralized water.

Distilled or R.O. (reverse osmosis) water can be added to tap water during water changes to help bring the GH down. You’ll also want to add Indian almond leaves or driftwood, which both contain tannins that help push the water towards acidity.

Coupled with generous feedings of live and frozen food, you’ll see the females begin to breed.

In the wild, shoals of Otos find shallow water where the weeds are thickest to deposit their eggs. The males compete to be in place the moment when the female is ready to lay her eggs.

Rather than being selective the female accepts the first male that’s ready when she is. So you’ll likely see your males chasing your female(s) constantly, trying to be first in line.

Once the eggs are laid Dwarf Otocinclus provides no parental care. Fortunately the young are very self-sufficient once they hatch.

They absorb their egg yolk in just a few days and immediately begin grazing eating algae and biofilm, making your work very easy. And being vegetarians Dwarf Otocinclus won’t eat their eggs or fry.

How Can I Tell if an Otocinclus Catfish is Pregnant?

Once a female begins producing eggs her belly takes on a faint yellow or orange hue. She will also visibly swell, which is especially visible from below or above.

Another way to tell if a female Octocinclus catfish is pregnant is to observe her behavior. Pregnant females may become more reclusive and spend more time hiding in the vegetation.

When an Otocinclus clings to the aquarium glass both the eggs and her swollen stomach are more easily visible.

It’s important to note that not all females will display these behaviors or physical changes, so it’s always best to keep a close eye on your Octocinclus catfish population and monitor their behavior and health to identify any potential pregnant females.

To breed Octocinclus catfish correctly always remember, as egg scatterers, they provide no parental care after they spawn.

In fact, they will likely eat their eggs within a few hours. So any plants that the eggs attach to should be removed in order to save the fry.


Frequently Asked Questions for Otocinclus Catfish Care

How Many Otocinclus Catfish Should be Kept Together?

Grouping Otocinclus catfish in a freshwater aquarium can be a delightful experience, as long as you keep 4-6 of these creatures together.

Where Can I Buy Otocinclus Catfish?

Finding a suitable place to purchase these fascinating fish is easy, as they can be procured from pet stores or fish store that cater to aquarium fish enthusiasts or obtained through online retailers.

How To Breed Otocinclus Catfish?

If you are seeking to breed Otocinclus catfish, be sure to create an environment that is both mature and provides ample hiding spots, along with a stable food source. Water conditions play a vital role in their reproductive success as well.

Are Otocinclus Catfish Hardy?

Although they are known to be hardy fish, maintaining good water quality and providing proper care is imperative to their overall health.

Are Otocinclus Catfish Nocturnal?

As diurnal creatures, Otocinclus catfish are active during the day and rest at night.

Can a Betta Fish Live With a Otocinclus Catfish?

Betta fish and Otocinclus catfish can coexist peacefully with other fish, but it is important to remember to provide sufficient hiding places for the latter, in order to prevent any aggression from the former.

What are the Common Health Issues in Otocinclus Catfish?

Some of the most common health problems faced by Otocinclus catfish are stress and illness, often caused by poor water quality, unbalanced diets, and overcrowding.

Is the Dwarf Sucking Catfish the Same as Otocinclus Catfish?

Yes, the term “Dwarf Sucking Catfish” is another name for the Otocinclus catfish. They are known for their algae-eating habits and their ability to attach themselves to surfaces using their sucker-like mouths.

Can I Keep Chinese Algae Eaters with Otocinclus Catfish?

While both Chinese algae eaters and Otocinclus catfish are known for their appetite for algae, they have different temperaments. Chinese algae eaters can become aggressive as they mature, especially towards smaller fish. If housed together, it’s essential to monitor their behavior closely and provide ample hiding spots to avoid potential conflicts. In general, it might be best to keep them in separate tanks or with compatible tank mates.

What Tank Mates Can I Keep Dwarf Otocinclus With?

Otocinclus are compatible with any peaceful fish community fish 3 inches and under; the smaller, the better!

My Tank is Out of Algae Wafers! What Can I Feed my Dwarf Otocinclus?

Prepared algae wafers, blanched soft vegetables, and dried nori strips are all great for Otos!

How Do I Raise Baby Otocinclus?

The fry are algae eaters, just like their parents!

Want to Learn More?

If you still have questions about the Octocinclus Catfish or would like to show off your tank, be sure to join our Facebook Group to join the discussion!



In conclusion, Otocinclus catfish, commonly known as oto catfish, is a popular freshwater fish species that is native to South America – suitable for freshwater aquariums. They are peaceful, hardy, and can help control algae growth by eating it, making them an ideal addition to a healthy fish tank environment.

Otocinclus tank mates should be other peaceful fish, and the minimum tank size for a group of oto catfish should be 10 gallons. Breeding otocinclus is possible, but it is not easy and requires a well-maintained tank with enough algae, suitable parameters, and a water temperature that mimics their natural habitat in South America.

Tank owners should provide fresh veggies and catfish pellets as a supplement to their diet, and also keep the tank clean and free of leftover food. A planted aquarium with slow-growing plant species and slow-flowing water would be best for these little catfish.

In a pet store, common otocinclus species include otocinclus affinis and otocinclus vittatus, and otos tend to prefer slow flowing streams and small rivers in their natural habitats.

Tank owners should consider their water parameters, algae eating behavior, and water temperature when selecting an oto catfish, and ensure they have a gallon or bigger tank to provide enough room for these active and algae-eating fish.

Overall, otocinclus catfish are an excellent addition to any tank water fish, adding color and helping to keep the water clean and healthy.


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