plecos are completely unecessary for the health of the tank. however they are very cool looking fish and i can understand wanting one just because it is unique or you like the fish. however, i do not agree with having them with the misguided belief that they somehow clean the tank of algae or whatever else. yeah, some of them do eat algae, but most of them are picky about the types of algae they will eat, and many grow out of eating algae and turn to a more carniverous diet. also, ANY and ALL algae eaters need their diet supplimented with blanched veggies, algae wafers, sinking pellets, etc.