I feel like sharing a picture of one of four otocinclus catfish that my younger brother has. This individual is in his 5 1/2 gallon fry tank. He doesn't have anything special in the tank, filtration is a sponge filter and there is some anarchis and hornwart growing, but not much. There is no heating so the temp is around 70-72. She (pretty sure this one is a female because of its width) shares the tank with 12-15 platy fry and a second oto (thinking male because it isn't as wide). I couldn't even keep 2 otos going in my planted 46 gallon tank so I am not sure how this is working! Sorry for the blurry picture.