Hatchet fish

The lovely hatchetfish is a mirror-sided fish of the twilight zone, the dim water where the last daylight fades out. It sits deep by day, around 300 to 600 metres, and rises to between 100 and 300 metres after dark. Its silver sides and its light organs work together to hide it: seen from below, the fish blends into the weak light coming down from the surface, so neither hunters nor prey pick it out. It feeds at dusk, mainly on ostracods, the tiny shrimp-like animals that live inside a hinged shell, and also on copepods and other small drifters. It grows to 8.3 cm.

Also known as: hatchet fish, lovely hatchetfish, silver hatchetfish, hatchetfish, marine hatchetfish, lovely hatchetfish, lovely hatchet-fish

Deep-sea hatchetfishes all share the same axe-blade outline, so shape alone will not settle it. Look instead at the pair of spines on the gill cover. On this species the lower one drops straight down and then curves outward, while the upper spine is short and points out to the side.

A very deep, thin body that looks flattened side to side, like the blade of a small axe. The flanks are bright silver. A row of light organs runs along the underside. The eyes are large, as in most fish of this depth. Maximum length is 8.3 cm.