A large, widely distributed family of small, mostely freshwater fish. The head is flattened and the mouth terminal and wide. They often hunt at the water surface. There are some 2500 species and varieties of Killifish. They are found in Asia, Africa, Europe, South, Central and North America.
Several species become very large for the aquarium.
But some species of suckermouth catfish, do stay small enough for most beginners to keep. The Bristlenose or Bushynose Plecos of the genus Ancistrus possess, as their common names imply, numerous projections from the area between their eyes and mouth. Within each species the bristles are larger on the male, especially near breeding. In fact, Bristlenose Plecos are among the few Loricariids to be successfully spawned in the home aquarium. Otocinclus Cats, often just called Otos, are the smallest Loricariids and will clean algae from live plants without hurting any but the most delicate of them.