Gobies are one of the largest families of fish comprised of over 2000 separate species. Although the majority of goby species exist in marine environments, there are several species of gobies that live in brackish and freshwater environments. Gobies are usually small and torpedo shaped. They are characterized by their morphed pelvic fins which are fused together to form a disc type sucker. When keeping gobies in an aquarium, it is not uncommon to see them latched onto pieces of aquarium décor or the tank walls using their sucker. Gobies are one of the most diversely colored species of fish and come in shades of red, orange, yellow, blue, green, brown and black.