Remarks: Common otos are small, algae-eating fish from South America. They rarely exceed 1.5″ in length and prefer to live in high numbers. It is recommended to keep them in a school larger than 10, but fewer numbers are okay in small tanks. They do a remarkable job cleaning leaves, wood, rocks, and glass of green and brown algae, and there are some reports of this species eating black beard algae as well.

As this species doesn’t have much in the way of defense and is very small, common otos should not be kept with aggressive species or those big enough to swallow them. They also require high levels of dissolved oxygen and do not tolerate poor water quality so heavy filtration and frequent water changes are a must. If a tank has high flow, it can be very entertaining to watch them play in the current.

What comes along with their amazing ability to clean up algae is a very high metabolism requiring that otos be able to graze 24/7. For this reason, they should not be added to a tank that does not yet have algae present and should be fed many frequent, small meals. Vegetables such as zucchini and green beans can be an excellent treat to ensure these little catfish remain happy and healthy.