Dealfish

Dealfish

  • Scientific name: Trachipterus arcticus
  • Also know as: Northern Dealfish, Ribbonfish
  • Size: Usually 4ft in length but can reach 8ft
  • UK minimum size: N/a
  • UK shore caught record: N/a
  • IUCN Status: NE (Not Evaluated)
  • Distribution: Widespread distribution being found throughout the North Atlantic Ocean. In Europe this species is found from Greenland and Iceland to Scandinavia and in parts of the North Sea, but appears to be absent from the Mediterranean. Only found around the British Isles as a rare visitor.
  • Feeds on: Believed to feed on small fish and squid.
  • Description: Distinctive looking fish which has elongated, slender, bright silvery body which is free of scales and sometimes has a number of large black spots present. Dorsal fin is pink to reddish in colour runs the entire length of the body. Tail is very small and also pink/red in colour. No anal fins are present and pectoral fins are very small. Eyes are extremely large and the mouth can be extended outwards when feeding.

The dealfish is a rare and unusual species of fish which, although rare, is found around the UK on a sporadic basis. While the term ribbonfsh is sometimes used to describe this species this is technically incorrect as ribbonfish is the family which this species belongs to and there are ten separate species of ribbonfish found around the world. However, the species featured on this page is the only one found in British waters on anything approaching a regular basis.

Dealfish are a striking looking species due to their slender, laterally compressed body which is bright silver in colour and their reddish to pink dorsal fin. They are found predominantly in the northern and western areas of the Atlantic Ocean. Dealfish live in deep water far away from land masses, although they live in the middle of the water column at depths of around 200 – 500 metres and are do not live and feed on the seabed.

Life Cycle and Feeding

Little is known of the life cycle and breeding patterns of the dealfish. They are thought to spend most of their life as a solitary fish, although dealfish have been known to gather together in large numbers from time to time. However, it is unknown whether this is due to spawning, gathering to feed on an abundant food source or another as yet unknown phenomena. Although this species is a predator the mouth of the dealfish is toothless. It mostly feed on the small fish and squid which it finds in its mid-water environment.

Dealfish are sometimes found washed up on beaches around the British Isles, especially in northern areas of Scotland. It is believed that dealfish which find themselves in shallow waters become confused and disoriented by being out of their deep water environment and then become caught up by the tide and wind and end up forced onto beaches.

Commercial Value

Dealfish are sometimes caught by commercial vessels trawling for pelagic species such as blue whiting over deep water, as this blog post shows [external link]. However, dealfish have no commercial value and the flesh of this species is, by all accounts, an unpleasant, gelatinous consistency. Any dealfish caught by commercial vessels are likely to be discarded at sea.

Other Species of Ribbonfish

Scalloped ribbonfish (Zu cristatus)

The scalloped ribbonfish (Zu cristatus) is another species in the ribbonfish family.

As previously stated dealfish are one of the ten species of ribbonfish which are found around the world, split across three genera. Other species include the slender ribbonfish, blackflash ribbonfish and the scalloped ribonfish. However, Trachipterus arcticus is the only species which is found in British waters. There is evidence to support that dealfish could be split into two separate species, with dealfish in the Northern Atlantic being different to those found in the Western Atlantic. Some reports recognise this by referring to Northern and Western Dealfish species. However, this area still requires further research and scientifically there is still only one species of dealfish recognised.

The species known as the red bandfish is also sometimes referred to as a ribbonfish, although it is unrelated to the species featured on this page. Trachipterus arcticus also looks very similar to a much larger and rarer fish which is also a rare visitor to British waters – the giant oarfish, although the species are not closely related.