The Gobiiformes are an order of fish that includes the gobies and their relatives. The order, which was previously considered a suborder of Perciformes, is made up of about 2,211 species that are divided between seven families. Phylogenetic relationships of the Gobiiformes have been elucidated using molecular data. Gobiiforms are primarily small species that live in marine water, but roughly 10% of these species inhabit fresh water. This order is composed chiefly of benthic or burrowing species; like many other benthic fishes, most gobiiforms do not have a gas bladder or any other means of controlling their buoyancy in water, so they must spend most of their time on or near the bottom. Gobiiformes means "Goby-like".