When I was just getting into keeping fish I had no clue as to what I was doing, so I made all the usual mistakes. After awhile I noticed that algae was growing on the glass and on everything else. I went to a pet store to see what they had, I looked for some chemical that would kill the algae. While I was looking a clerk came up to me and asked if he could help me, I told him what the problem was and he says all I need is an algae eater. He takes me over to show me an algae eater. I look in the tank and there is this fish that look like it can kick ass, not eat algae. He tells me the fish is called a plecostomus or for short a pleco, well I thought this fish was cool so I bought it and put it in a 10 gallon tank. He was around 3" long and I thought he was great till he started getting bigger and made a mess of my tank. Unfortunately he died, most likely due to my ignorance and the lack of space that he needed to have a healthy live. I now know that the common plecostomus will get very large with the common variety getting to be almost 18 inches (46 cm) and will out grow most aquariums under 55 gallons. There are varieties that don't get as large, such as the Bristlenose Plecostomus which reaches about 5 inches in size as adults. Plecos are interesting fish, but they are not suitable for many aquariums. If you are going to get a fish to eat algae I would either go with an Otocinclius, aka "Otto" catfish, or a Siamese algae eater. Ottos stay pretty small in size: 2"+. Siamese algae eaters get a bit bigger than that: around 4".