The Otocinclus affinis is a very small suckermouth catfish from near Rio de Janeiro, Brazil. It has become a very popular fish because, being vegetarian, it makes an excellent algae eater (especially brown algae) that doesn't harm plants. They live well in groups and are often seen stuck on the aquarium glass, for which the brazilians call them "Limpa-Vidros" (glass cleaners). They don't seem to take changes too well, though, being prone to unexplained deaths when moved to new tanks.