Overview
The Dealfish (Trachipterus arcticus) is an enigmatic, ribbon-like lampriform fish inhabiting the dark mesopelagic and bathypelagic depths of the North Atlantic Ocean. Known historically to Scandinavian fishermen who viewed its rare beach strandings as mystical portents, this silver, serpentine wanderer swims vertically through twilight ocean layers, propelled by undulating undulations of its brilliant crimson dorsal fin.
Biology and Physical Characteristics
Possessing an extremely laterally compressed, blade-like body resembling a wooden deal plank (from which its common name derives), Trachipterus arcticus is coated in delicate, mirror-like silvery guanine crystals rather than standard scales. Its most striking feature is a continuous, bright crimson dorsal fin running the entire length of its spine, crowned at the head with an elongated feather-like crest. It has large, circular golden eyes adapted to collect downwelling photons and a highly protractile jaw that shoots forward to engulf swimming prey.
Behavior and Ecology
The dealfish displays a unique vertical swimming mode known as amiiform locomotion. Hovering head-upward at an angle in the water column, it remains nearly stationary while rippling its dorsal fin, blending into downwelling twilight as an almost invisible vertical sliver. Using its massive eyes to spot silhouettes of squids, lanternfish (Myctophidae), and pelagic krill against the faint surface light, it snaps its accordion-like mouth open, generating powerful negative suction to draw food inside.
Conservation and Human Impact
The IUCN assesses Trachipterus arcticus as Least Concern due to its vast bathypelagic range across northern oceans. It has no targeted commercial fishery value because its soft, watery, gelatinous flesh is unpalatable for human consumption. It is occasionally taken as incidental bycatch in deep-sea bottom trawls targeting Atlantic cod or redfish, and winter storms occasionally wash disoriented specimens onto Scottish and Norwegian shores.
Interesting Factoid
The name ‘Dealfish’ comes from an archaic Norse and Scottish term for a deal (a wooden plank or sawn timber board), honoring the fish’s extraordinarily flat, razor-thin ribbon body.
Last updated: October 2026