What is "barreleye"

n. A small, deep-sea osmeriform fish of the family ''(taxlink Opisthoproctidae family noshow=1)'', with barrel-shaped, tubular eyes which are generally directed upwards to detect the silhouettes of available prey.

Barreleyes, also known as spook fish (a name also applied to several species of chimaera), are small deep-sea argentiniform fish comprising the family Opisthoproctidae found in tropical-to-temperate waters of the Atlantic, Pacific, and Indian Oceans.

These fish are named because of their barrel-shaped, tubular eyes, which are generally directed upwards to detect the silhouettes of available prey; however, according to Robison and Reisenbichler, these fish are capable of directing their eyes forward, as well. The family name Opisthoproctidae is derived from the Greek words opisthe ("behind") and proktos (" anus").