Fin

The best-known ´traditional´ algae eater is the common plecostomus, but this particular fish is a heavyweight contender and will grow to huge proportions (45cm 18"+) so is suited only to the very largest of aquariums. A good alternative is the bristlenose plec (ancistrus sp.), which is very similar in appearance, yet only reaches a manageable 15cm (6"). Bristlenose plecs are one of the suckermouth catfishes (Loricarids), which have evolved to eat algae as their primary food source. The ´Suckermouth´ is a highly developed mouth that will rasp away at algae but is also used to scrape off the very top layers of established driftwood. The driftwood eaten by the fish is actually an important part of its dietary and feeding systems so to keep any of the suckermouth catfishes it is a vital piece of decor. There are many other suckermouth catfishes to consider, including some colourfully marked unclassified ´L number´ fishes. It is worth trying to find out as much as you can before purchasing, as some of these fish may require soft water or may grow to significant sizes. A couple of good choices for the smaller aquarium would be the otocinclus sp. or peckoltia sp. (dwarf plecs) Both these groups of fish are peaceful and the biggest will grow no bigger than a few inches. Suckermouth catfishes will usually avoid established fiberous, brush, or blue-green algae but will help to prevent its formation.
Some suckermouthed catfishes can be territorial and may squabble but damage is rarely done providing each fish has its own retreat and all will mix with tankmates of any size within reason. Although there are cases of some suckermouthed catfishes attacking fish, particularly laterally compressed species (angelfish, gouramies etc.) these are rare and usually occur when the victim fish is producing excess mucus due to illness. It would be tempting fate however to mix these fish with discus which are slow moving and produce a particularly tasty brand of mucus.