Otocinclus FAQ

Below are some Frequently Asked Questions about the Otocinclus catfish. Some of them are questions that have been asked directly of me, and others are ones I have heard asked in online forums. Feel free to email me any questions you have to paul_apgar AT hotmail.com.

Questions/Answers

Do otocinclus like salt in the water?
No. Otocinclus come from the freshwater orinoco river system in the amazon, which has zero salt in the water. It is actually very soft water. They are the same as corydoras species in this respect. They should not be kept in brackish water conditions or extremely hard water.

Do otocinclus require driftwood?
No. This has been going around for a while, because some people confuse otocinclus needs with some of the "wood catfish" needs, such as the gold nugget pleco. Otocinclus do not suck on the wood to get at the fiber and other materials found therein, but they may enjoy any algae that grows on such driftwood, especially if it reaches near the surface of the tank and receives a lot of light. But otocinclus do not require wood, either in their diet, or in their environment.

Can I put otos in with goldfish to help clean the algae?
No. While otocinclus would enjoy the amount of algae that messy goldfish produce with their wastes, the enjoyment would end there. Goldfish and otocinclus have such different needs and requirements, that the two cannot live together. The major requirement is water temperature, where goldfish do not like water above 70° F, the otocinclus species cannot tolerate water under 70° F for very long. Goldfish produce so much waste, and are able to withstand their own pollution levels so well, that the otocinclus would not be able to meet such water conditions and survive.

My otocinclus catfishes just sit around and do nothing all day, are they sick?
Sometimes otocinclus do not feel safe out in the open during the day, and only are active at night. This matches how most Loricarids behave. Only until they are used to their surroundings do they begin staying out in the open for long periods of time. It would be rare to find all your otos out in the open, however, as most fishkeepers report it being impossible to count all the otos you have in a tank, because some are almost always hidden at any given point. Makes for a good reason to buy them in large groups!

My otocinclus belly looks really fat and bloated, is it healthy?
Well there is a healthy fat, and an unhealthy fat. Take a look at this picture to see if your oto looks that way. There are a few warning signs that the fatness is not healthy: red streaks (infection), scales sticking out slightly (dropsy), or a particular bump in one area (tumor).

My oto is attacking other fish! What can I do?
Well there have been a few reports of otocinclus which attack slow moving flat-bodied fish, such as discuss, or angelfish. It must be mentioned that sometimes otocinclus are slightly territorial with each other, but they would most likely never attack another fish. I think this behavior could mean that the otocinclus is very hungry and trying to latch onto any surface that may have food, be it an organic surface or non-organic. If it is one particular otocinclus then move him to another tank (with other otos), or buy more otocinclus so they can form a group that may entertain themselves and not go after individual fish.

How can I tell a male oto from a female oto?
It is not that simple to tell the gender of an otocinclus, since the males and females have the same coloration. You need to wait until they're nearly adult size before the differences are noticed. As with corydoras, the otocinclus catfish females are usually larger and more plump around the midsection (when viewed at from above).

The colors on my otocinclus are faded, are they sick?
Most fish, when stressed out, will exhibit loss in color and appear "washed out". This is also true with otocinclus. At the store the otocinclus may appear to have very light gray top, a thin stripe down the middle. When taken home and taken care of properly (clean water and lots of greens) you will notice that the once-gray fish turn a darker gray (sometimes even brown), and now have a thick black stripe running through the middle of their bodies. I would recommend stepping up water changes to 30%-40% twice a week, and make sure gravel is clean and the fish have plenty to eat.