Plecostomus Catfish, Plecos are notorious algae eaters and will help keep an aquarium clean. The are lots and lots of species of Plecostomus. This one is often just called a Pleco, or a Regular Pleco, or sometimes a Trinidad Pleco. It's a good aquarium fish, but ... it can grow to be too big for all but the biggest aquariums. Fortunately there are many other species of Plecos that are smaller.