A group of fish is not a mophyletic and includes some different classification groups. Fish are the popular name of animals which has the shape of fish. Most of fish bear jaw, but some fish do not have jaws. Formation of jaw is an important event in the history of early vertebrates. Jaws are originated from visceral arches. Mandibular and hyal arches play a role of jaw apparatus. The jaw of most fish are supported by hyomandibular which are upper part of hyoid arch. Fish obtained various jaw structure and mechanism.