Ophichthus longipenis, known commonly as the Slender snake eel in Mexico, is an eel in the family Ophichthidae (worm/snake eels). It was described by John E. McCosker and Richard Heinrich Rosenblatt in 1998. It is a marine, tropical eel which is known from the eastern central Pacific Ocean, including Mexico, El Salvador, Guatemala, Honduras, Nicaragua, Costa Rica and Panama. It dwells at a depth range of 0 to 69 metres (0 to 226 ft), and inhabits sand sediments. Males can reach a maximum total length of 58.7 centimetres (23.1 in).