Otocinclus are easily one of our favorite freshwater fish.

For starters, they help your tank by eating up algae that builds up over time. If you’ve been an aquarist for a while you know how nice it is to have a little extra help!

Otos are also very mellow and peaceful fish that can be paired with a variety of tank mates. You never have to worry about them starting a fight.

Lastly, they’re a breeze to care for. Otocinclus are about a low-maintenance as it gets.

Oh yeah, and they’re super cute! We just love these little guys!

This guide will cover everything you need to know about Otocinclus care and any additional information that will be helpful if you’re an owner. We had a ton of fun putting this one together.

What Are Otocinclus?

Otocinclus are considered a small catfish that live in freshwater. These fish come in roughly 19 different species of the Loricarlidae family.

Some people call these docile fish “dwarf suckers” or “otos” as appropriate nicknames for these fish and their outstanding algae eating abilities. These guys can make a significant impact on the quality of the water in your freshwater aquariums.

Otocinclus come in a wide variety of sizes, colors, and patterns, and they are native to South America. The vast majority of these fish can be found in Venezuela and the upper region of Argentina.

One interesting thing to note is that these fish prefer living in smaller rivers. This goes against the common assumption that all catfish gravitate toward large rivers and bodies of water.

Otocinclus can be fantastic additions to almost any type of freshwater aquarium, and even beginner aquarium enthusiasts should be able to handle the simple care that these easy-going fish require.

Otocinclus Lifespan

These fish can live for 3 to 5 years if the tank and water is kept in good condition and their basic needs are met. Like any animal, poor care and living in a stressful environment can significantly impact their life expectancy.

What To Look For When Shopping Around

A trick before purchasing these small catfish from a pet store is to choose fatter fish. Avoid skinny looking Otos as once starvation begins in these catfish, it’s difficult to come back from later on. This is a very common problem that new owners face, so be a bit picky when making your selection!

Also, look for healthy fish that have bright eyes and a bigger body size. Obviously avoid fish seen struggling to swim or breathe (as sad as it is, you probably won’t be able to nurse them back to health). Cloudy scales and eyes could indicate ich disease common in aquarium dwelling fish.

Appearance & Size

Most varieties of Otocinclus are small with adults rarely growing more than 2 inches in size.

Some of the smallest Otos measure only 1 inch in length. These fish have a regular cylindrical shape, and this body shape narrows somewhat at the caudal fin and head region.

Otocinclus on plant in aquarium

The fish has a larger mouth that suctions onto surfaces tightly as they suck in algae stuck on aquarium glass and even on live plants within their tank.

The colors and patterns that you’ll find on these fish are also very impressive. In our opinion, the beauty of Otos is seriously underrated!

One common trait you’ll notice is that most types of Otocinclus have a distinctive brown stripe that stretches down their body.

Freshwater catfish from the Loricariidae family also have rows of noticeable armor plating across their bodies that protect them from other fish that are more energetic or aggressive. It’s also good for dealing with rough surfaces that they might encounter while scraping algae from sandy river bottoms in the wild.

What Are the Different Types?

There are many different types of Otocinclus, and these peaceful fish make excellent additions to community aquariums due to their non-aggressive temperament.

Some of the most common types of freshwater Otocinclus include:

  • Common Otocinclus (Otocinclus vittatus)
  • Zebra Otocinclus (Otocinclus Cocama)
  • Golden Oto (Otocinclus affinis)
  • Silver Otos (Otocinclus vestitus)
  • Dwarf Oto (Otocinclus macrospilus)

Let’s take a closer look at each of them.

Common Otocinclus:

One of the most widespread and common species of Otocinclus, this variety can be found throughout the regions of South America sometimes even in parts of the Amazon River where other fish of their size tend to avoid.

When looking at the top of this fish, a brown speckled pattern is noted. Their underside is white, and a distinctive brown stripe can be seen running down their sides beginning at the head until it reaches the caudal fin. The other fins are typically transparent in color.

Zebra Otocinclus:

As the name suggests, this fish sports bold black and white stripes situated vertically from the back of its head down to the caudal fin. The fish also has horizontal stripes across the head as well. Since these stripes are not all perfectly straight, some people call this Otocinclus type Tiger Otos for short.

Dwarf Oto:

This type of Otocinclus looks much like the Common Oto at first glance. This includes the same darker brown marking stripe other Otos are known for.

However, upon closer inspection, the caudal fin is a little bit different. Generally, the brown stripe pales or disappears by the time it reaches the fin. There is also a noticeable blotch found on the tail portion of this Oto variety.

Golden Oto:

Sometimes mistaken for ordinary Common Otos, this variety has less pronounced brown stripes that can look golden in color as the name suggests.

Silver Otos:

Again reflecting their name, the Silver Oto features brown color patterns that look more silver. Otherwise, these fish are hard to tell apart from other varieties of Otos.

Otocinclus Care

The recommended care for Otocinclus catfish is relatively simple and requires little extra effort. This is part of what makes them so appealing to tank owners, they’re super low-maintenance!

In general, these fish spend a lot of time near the bottom of the tank since this is where the algae tends to be. They are also adaptable and can withstand changes in their environment better than other fish of their smaller size.

They’re also very docile and get along with almost any other freshwater aquarium species. This means they’re unlikely to get themselves into trouble in your tank. In the wild, these fish travel and live in schools which helps them stay safe as well.

Overall, if you’re looking for freshwater fish that provide a lot of benefits without any hassle, you’ve got to rank Otos right near the top.

Tank And Water Conditions

In their native South American habitats, these fish often attach themselves to rocks, gravel and other river bottom surfaces that contain algae growth. They tend to graze on algae and often stay in groups to better protect themselves from larger fish.

Here are the water parameters you want to aim for:

  • Water temperature: This should be maintained at a warmer 72°F to 79°F.
  • pH levels: This should be kept neutral in a range of 6.8 to 7.5
  • Water hardness: These fish do well in soft water with readings no greater than 15dH for best results.

Even though Otos tend to keep their tank conditions cleaner since they’re algae eaters, it is still important to perform water changes every week to two weeks. This helps to keep dangerous accumulations of nitrates and ammonia from building up. Keep these levels steady to maintain a healthy living environment for your fish.

Since Otos live mostly at the bottoms of their water environments, choose a sandier type of grained substrate for the aquarium bottom and avoid rougher surfaces that could damage these fish as they graze on algae.

Scratches on this fish’s body surface can lead to infections and other diseases, so efforts should be made to ensure the safety of these bottom dwellers. Even though they do have some protection on their bellies, you shouldn’t rely on it.

Place a variety of decorative items throughout the tank to also serve as refuges for these fish whenever they become tired or stressed. Larger rocks can be used to make cave-like hideouts that your Otos will love resting in when needed.

Although Otos prefer oxygenated water, no special air pumps are required for aquarium life. Standard aquarium pumps and lights work fine.

Otocinclus Tank Size Requirements

The minimum Otocinclus tank size should be around 10 gallons. This means you can safely house 4 to 6 Otos, and more can be added as the tank size increases.

Plants should be added to the aquarium, and natural light with some shading is preferred to help these fish thrive.

Food & Diet

Otos are considered herbivores, which means that they are vegetarians. Although they eat mainly algae in their native habitats, fish owners should provide other food for aquarium living Otos.

Life plants in the aquarium will provide an algae food source, and your easy-going Otos can use the plant bases as quick hiding places as well.

Pet stores that sell fish often have algae wafers that can be used to feed them too. Other kitchen staples can also be used, and some terrific natural food items include:

  • Zucchini
  • Lettuce
  • Spinach

Chop these ingredients up to smaller pieces, and add them to your tank several times a week you want to give them some variety. Make sure that the food source sinks down to the bottom. 

Any leftover food not eaten in 24 hours should be removed from the aquarium. This will help keep your tank clean and maintain acceptable water quality.

Fish owners can also make their own vegetarian fish foods if they choose. Remember to keep the food balanced, and never overfeed your fish.

Behavior & Temperament

As already stated, Otocinclus varieties of fish tend to be calm and docile in temperament. These fish won’t become aggressive towards other fish.

Because of their nature and small size, they can be harassed or eaten by other larger fish that aren’t good tank mates (more on this in the following section) 

Otocinclus staying on the bottom of the tank

Otos try to stay out of the way for the most part. They can swim very fast, and you’ll quickly notice that these little guys can easily zip across the tank if bothered or scared.

As we mentioned in the tank requirements section, it’s important for owners to provide hiding places in the aquarium so the smaller Otos have a refuge when disturbed by others.

Otocinclus tend to travel in schools, and it’s best to have several of these fish together when setting up an aquarium environment.

Ideal Tank Mates

There are many Otocinclus tank mates that you can consider. This is due to their pleasant and non-threatening personalities and behavior towards others inside of a tank.

You should avoid pairing these peace-loving fish with fish that are known to be aggressive in nature. Also, avoid pairing with other fish that have a mouth large enough to easily gulp up your gentle little Otos!.

Examples of fish to avoid include many Chichlids or the feisty Oscar.

On the other hand, good tank mate choices include:

  • Corydoras Catfish
  • Harlequin Rasbora
  • Dwarf Gourami
  • Zebra Loaches
  • Cherry Barbs
  • Tetras
  • Mollies
  • Guppies

Additionally, fish owners can add invertebrates like certain snails and shrimps to aquariums containing Otocinclus. A couple of tank mates that people like to pair with Otos are Amano or Cherry shrimp. Just make sure you have enough algae for everyone!

Breeding Otocinclus

Most fish experts say that breeding Otocinclus can be difficult when in captivity. However, it can be done with trial and effort.

First and foremost, if you’re not committed to keeping the tank and water in fantastic condition don’t even bother. Keeping the tank clean is essential for any successful breeding to take place.

Other tank conditions also need to be near perfect for breeding to work. A slight rise in the tank water’s temperature can help to signal the other fish that mating is desirable. This is how Otocinclus breed in their natural environments.

When the fish are ready to mate, you might notice male Otos chasing female ones. The male has to fertilize the female’s eggs normally laid out in small piles across the tank floor.

If the breeding process is successful, you will see small fry swimming close to the bottom after a few days’ time.

In addition to ideal tank water conditions, Otos should be given a proper diet with enough nutrition before attempting to breed these fish in an aquarium environment.

Wrapping Up

As you can see, there are a number of benefits to having Otocinclus in your tank. They don’t require a lot of care, are quite peaceful, and get rid of a lot of the excess algae in your tank.

They’re also a joy to watch swim around your aquarium and look great!

We highly recommend that you add some to your freshwater tank if you have tank mates that are a good fit. You won’t regret it!

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