Otocinclus catfish, or otos for short, are a species of very small herbivorous catfish. They are less than 2 inches long at maturity. Their small size makes them a popular addition to home aquariums to control algae growth.
Otos are very peaceful fish and can be kept in aquariums with practically any other species. They prefer to eat green algae that grows on the sides of the tank, the gravel and the plants in the aquarium. If there is insufficient algae growth in the tank, they need to eat some type of vegetation in addition to natural algae growth. They are industrious fish that spend a lot of time removing all traces of algae from the tank.