Otocinclus, the Wonder Cat!

The most common nuisance in a typical aquarium is the ever-abundant fiend known as algae. It can grow on your plants blocking light and restricting growth. It can grow on glass and block the view of the world you have created. In short, find a surface and it will grow! Short of periodically scrubbing every inch of your aquarium, or not allowing a single glimmer of light into your tank, what can be done to ward off this tormentor? Meet the Otocinclus, your aquatic lawnmower friend.

The Otocinclus is a dwarf sucker-mouth catfish that only grows to be about 2 inches long. The Otocinclus is a tiny, lovable catfish that loves to eat algae from your aquarium, glass, and other decor. They are not known for eating aquatic plants. They specialize in eating soft green algae; often this algae is hard to see without looking closely for it. The otocinclus can eat it before it grows out of control. The best part is that they are generally priced reasonably for what they do: usually anywhere from $1.99 to $5.99 per unit.

This little gem should be kept in peaceful tanks. Otocinclus are very healthy and can be kept with fry or even tiny dwarf shrimp. They thrive when they are able to learn with other members of their species. When stressed they will travel in a pack foraging for food. Most of the time, you’ll only see this behavior when you first introduce them to your tank. Once they settle in they should not feel threatened and will school less often.

Experienced aquarists will tell you that Otocinclus are a very resilient fish. They don’t often contract common illnesses that plague other fish. Their greatest weakness is not getting enough to eat during handling.

Unfortunately, Otocinclus are not spawned in aquariums very often. The majority of Otocinclus specimens that you purchase from a pet shop will come from wild captures. As with other wild caught sucker-mouth catfish, this makes for a perfect storm. Otocinclus are scooped up by the hundreds and transported to a warehouse where they’re fasted for a few days before they are shipped out. They arrive at a wholesaler where a few hundred of them are put into a bare-bottom aquarium with no decoration and poor lighting. This means that virtually no algae grows in the tank. Algae wafers are supplied, however, the sheer number of Otocinclus is too many to feed correctly. A week later they will be ready to go to the local pet shop. They are placed in a tank and fed by the pet shop. It is not easy to feed them, though, since most pet shops have a few dozen more Otocinclus. This is odd because they wouldn’t stock anywhere near that many plecostomus in the same tank.

Don’t worry – even through all that stress, Otocinclus can still thrive in your aquarium. Here are some tips that will help your new pet survive.

First, make sure you have algae in the tank for them to pig out on when you get them home. They’ll be hungry after a few weeks of not enough food. This can be achieved by placing them in a quarantine tank. Once they are hungry, you can turn the light off for about a week and then watch as algae grows.

Next, buy these fish the day after they come in to your pet store. This goes against conventional wisdom which says that you want to buy a fish that has been at the pet store longer to prove their longevity and lessen the shock of being transported too soon after arrival. Given that Otocinclus are typically grouped together in such abundant numbers – and are often put into tanks that can’t produce algae as fast as they can consume it – you want the stronger fish separated from the rest as soon as possible. Sometimes it is difficult to determine which fish have been around for the longest. It is important to take your Otocinclus back home, and to acclimate them in your quarantine aquarium that has been growing algae for the anticipation of their arrival. You’ll be able to reduce the amount of time they are starving since you already have a meal ready for them at home.

Otocinclus prefer peaceful community settings. Otocinclus are small and timid, so they can easily be out-competed in terms of food. Make sure you have algae for them to eat before adding them to your aquarium and you’ll be amazed at the algae-control one little fish can provide. Give this dwarf catfish a try and it’ll surely win you over. I know I couldn’t live without them!