About Enneapterygius atriceps (Jenkins, 1903)
This species, known commonly as the Hawaiian blackhead triplefin, has the scientific name Enneapterygius atriceps (Jenkins, 1903). It is classified within the Enneapterygius hemimelas species group. It is a small to medium-sized member of this group. Males of this species reach a maximum total length of 2.6 centimetres. Males can be told apart from females by their characteristic dark head colouring.