Lungfish are freshwater rhipidistian fish belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, including the presence of lobed fins with a well-developed internal skeleton. Lungfish represent the closest living relatives of the tetrapods.Mudskippers are amphibious fish. They are of the family Oxudercidae and the subfamily Oxudercinae. There are 32 living species of mudskipper. They are known for their unusual appearance and their ability to survive both in and out of water. They can grow up to 30 centimetres (12 in) long and most are a brownish green colour that range anywhere from dark to light.