Blacktail triplefin is a common name for several species of fish in the threefin blenny family (Tripterygiidae) and may refer to:
Enneapterygius bahasa, also known as the blacktail threefin, a species of threefin blenny known from reefs in the western Pacific Ocean Enneapterygius nigricauda, a species of triplefin blenny Enneapterygius similis, also known as black and red triplefin or masked threefin Helcogramma aquila
See also Japanese blacktail triplefin, Springerichthys bapturus