Definitions for "Anal Fin"
Keywords:  fin, caudal, ventral, unpaired, median
This fin is on the underside (ventral side) of the fishes body near the caudal fin and anus (hence its name).
The single median fin lying behind the anus, between the posterior end of the abdomen and the anterior end of the caudal peduncle.
A median fin located just behind the anus on the underside of a fish.