Dictionary of Ichthyology  

homocercal = type of tail fin in which the vertebrae generally turn upward at the hind end of the column, but which is externally symmetrical. The fin rays of the caudal are supported by hypaxial elements. Found in most Teleostei.

A = diphycercal in Polypterus, B = heterocercal in Acipenser, C = homocercal in Amia and D = homocercal in Salmo from Kingsley's "Textbook of Vertebrate Zoology, 1906. Photograph by Brian W. Coad.

Canadian Museum of Nature
www.briancoad.com