It likely has a worldwide distribution, having been first discovered offshore of Kalk Bay, South Africa, and subsequently reported from the Sea of Japan, southwest Florida, Clarion Island off Mexico, Hawaii, and India.

The anal fin contains five to 9 rays and in adults is split lengthwise to form two rows of nubbins.

[6] Eumenichthys is one of three lampriform genera known to possess ink tubes, allowing them to expel a black fluid from their cloacae as a defense against predators.

The ink tube is derived from a primitive gut and runs above and parallel to the intestine.

[3] A known predator of the unicorn crestfish is the longnose lancetfish (Alepisaurus ferox); a lancetfish 73 cm (29 in) long has been found that had swallowed a unicorn crestfish 55 cm (22 in) long.