caudal fin diphycercal tail An internally and externally symmetrical tail (caudal) fin. isocercal tail UBERON:4200053 In Dipnoi, may be secondarily acquired from the homocercal condition by loss of the real caudal fin and the gaining of a new one from dorsal and anal elements, e.g. in Gadidae. http://www.briancoad.com/Complete%20Dictionary%20latest%20version.htm