The common plecostomus, or common pleco, is a fish known as an algae eater. The common plecos are of great interest because they could be kept in either a tropical or cold water tank. These fish also do well at outdoor ponds.
Common plecos generally reach an adult size of about 8-12", though they can get larger. The common pleco is a type of catfish and is a "slime sucker", he will try to "clean" his tank mates if given a chance. This means that larger, slow-moving fish with thick slime coats should never be kept with a common pleco as the latter may accidentally kill the fish. Namely, they should never be kept with goldfish of any kind and they have been known to cause problems with Angelfish, Oscars, Silver Dollars and more.
Next, since these fish are marketed as an algae eater many people get the false impression that algae is all they need. On the contrary, common plecos are voracious eaters and need quite a variety of food in adequate quantities to stay healthy. Aside from tank algae you can also feed your common pleco algae wafers, zucchini, cucumber, peas, melon and virtually any other type of semi-soft fruit or vegetable you can think of as well as shrimp, shrimp pellets and flake fish food. Bear in mind that juveniles eat a lot because they're growing and adults will eat a lot because they're a pretty large fish.
If you're planning on adding a common pleco to your home aquarium, make sure that you have at least a 55G tank with large open spaces on the bottom that will allow the pleco to move freely without destroying anything. As the fish matures, it may grow out of this tank size but 55G is a good starting size. Be sure to feed them a variety of food and, especially if it has tank mates that are aggressive eaters, make sure that it's sinking food of some kind.
You may be thinking that this sounds like an awful lot of space and work just for an algae eater and you'd be right. If all you want for your aquarium is something that'll suck up algae and make itself scarce the rest of the time, consider some smaller types of plecos, otocinclus or algae nibblers such as platies, juvenile apple snails and gouramis.
