The common pleco (Hypostomus plecostomus or suckermouth catfish) is an aquarium favorite, beloved for eating algae off of fish tanks. They are often purchased when very young and small, but beware: they can grow up to 2 feet in length, and will require a 50 gallon aquarium minimum when fully grown! If your tank isn't large enough, look for one of the common pleco's smaller relative, such as the bristlenose pleco.Common plecos are nocturnal and not very active during the day; make sure you don't forget to turn the lights off at night. They are also herbivores (and opportunistic omnivores) who eat algae, algae pellets, and blanched peas, zuchinni, and the occasional shrimp pellet.