• Scientific name: Chimaera monstrosa
  
• Also know as: Rat-fish, Chimaera
• Size: Up to 5ft (including tail)
• UK minimum size: N/a
• UK shore caught record: N/a
• IUCN status: VU (Vulnerable)
• Distribution: Found in the deep water of the Rockall Trough to the west of Ireland and the Faroe-Shetland Channel to the north of Scotland, although can be found elsewhere around the British Isles and throughout Europe.
• Feeds on: Marine invertebrates, crustaceans, prawns and shrimps.
• Description: Broad head with a long, tapering body which continues along to a whip-like tail. A large spine which secretes venom is situated in front of the first triangular dorsal fin, and the second dorsal fin runs the length of the body and is edged black on the top. Pectoral fins are large and broad. The lateral line is light in colour and almost meets the large eyes which are green in colour. Rest of body is usually mottled dark and light brown, usually with silvery tint and a pale underside.

Rabbit fish are a medium-sized deep water fish. The total length of a rabbit fish can be as long as 5ft (but this includes the long, thin tail) and the maximum weight is around 5 – 6lbs. The rabbit fish is classed as a deep-sea fish and is generally found in waters between 100 and 1000 metres deep. This is not as deep as most of the other species featured in this section and means their range extends beyond the Rockall Trough and Faroe-Shetland Channel areas. Rabbit fish are thought to come into waters as shallow as 40 – 50 metres in summer months.

Distribution

This species is found throughout Europe wherever there is sufficient depth of water. It is found around the British Isles (especially in the Rockall Trough and Faroe Shetland Channel, but elsewhere as well) and its range extends southwards throughout the Mediterranean Sea. It is also found northwards into Scandinavian waters as far as Svalbard and into the north east Atlantic along the coastline of Greenland.

Feeding and Reproduction

Rabbit fish feed on the seabed. They do not hunt other fish or squid but instead move slowly in small groups where they feed on any of the bottom-dwelling creatures they come across such as deep-sea prawns and shrimps, crabs and other crustaceans as well as all manner of marine invertebrates. Lacking a tail fin rabbit fish move in an ungraceful and slow fashion, relying on the power generated from their pectoral fins. Little is known about the spawning of rabbit fish but the male has a retractable clasper on its forehead which it may use to hold the female in place while the eggs are fertilised. Like many deeper water fish species, the rabbit fish is long-lived, slow-growing and late maturing. It is thought that rabbit fish can live for over thirty years and do not reach sexual maturity until they are at least ten.

Human Interactions with Rabbit Fish

The first dorsal fin of the rabbit fish contains a long and pointed spine which contains venom. While this venom is thought to be relatively weak in terms of the impact it has on humans the spine itself can inflict injuries on people handling this species. While rabbit fish do not have any real commercial value they are caught in large numbers as the bycatch of deep-sea trawlers which can have a significant impact on numbers. The IUCN (International Union for the Conservation of Nature) previously classed the rabbit fish as Near Threatened but this was changed to Vulnerable (with a decreasing population trend) following a reassessment in 2019. The IUCN class commercial fishing as the biggest threat to this species. Rabbit fish make up 15% of discards in trawl fisheries and up to 50% in some deep-sea gill net fisheries.

Other Species of Rabbit Fish

There are around fifty other species of rabbit fish found across the world, with around one sixth of these being found in British and Irish waters, most notably the large-eyed rabbit fish (Hydrolagus mirabilis) and the small-eye rabbit fish (Hydrolagus affinis). The tropical species of fish from the Siganidae family are also known as rabbitfish but have no connection to the species featured on this page.