Otocinclus, the Wonder Cat!

The most common nuisance in a typical aquarium is the ever-abundant fiend known as algae. It can block light and stunt growth by growing on your plants. It can grow on glass and block the view of the world you have created. It will grow if you give it a place to live. 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. This little guy is a specialist in soft green algae. It can be hard to spot this algae without paying attention. The otocinclus will eat it before it grows too long and gets 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 don’t have a mean bone in their body and can be housed with fry and even baby dwarf shrimp. They thrive when they are able to learn with other members of their species. If they feel stressed, they may travel together in a group to hunt for food. This behavior is most often seen when they are first introduced to their 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 biggest weakness is their inability to get enough food during handling.

Unfortunately, Otocinclus are not spawned in aquariums very often. Wild caught specimens will usually be what you get from your pet shop. As with other wild caught sucker-mouth catfish, this makes for a perfect storm. Otocinclus, which are often taken by the hundreds, are then transported to a warehouse. They are kept there for a few days until they are ready for shipping. 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 virtually no algae is grown in the tank. Algae wafers are supplied, however, the sheer number of Otocinclus is too many to feed correctly. A week or so later, they should be on their way to your local pet store. The store will place them in a nice tank and provide food. It is not easy to feed them, though, since most pet shops have a few dozen more Otocinclus. This is unusual because they don’t usually stock as many plecostomus within the same tank.

Don’t worry – even through all that stress, Otocinclus can still thrive in your aquarium. Here are a couple of simple tips that will greatly increase the survivability of your new pet:

First, make sure you have algae in the tank for them to pig out on when you get them home. After a couple weeks of poor feeding, they’re plenty hungry! 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. This will lessen the time they spend starving as you’ll already have a buffet waiting for them at home.

Otocinclus thrive in peaceful communities. Given their size and timid nature, they are easily out-competed for 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 can’t imagine my life without them.