butidae is a family of sleeper gobies in the order gobiiformes. the family was formerly classified as a subfamily of the eleotridae but the 5th edition of fishes of the world classifies it as a family in its own right. molecular phylogenetic analyses have demonstrated that the butidae are a sister clade to the clade containing the families gobiidae and gobionellidae and that the eleotridae is a sister to both of these clades. this means that the eloetridae as formerly classified was paraphyletic and that its subfamilies should be raised to the status of families.