This page features profiles of some of the species of rare and unusual fish which are not found regularly enough around the UK to have their own profile, but can be found in British waters from time to time. Scroll down to read through the different species, or click on the links below to jump to a section.

Mediterranean Scaldfish – Rudderfish – Cornish Blackfish – Bogue – Blue Runner – Long Rough Dab – Sand Sole – Red Scorpion Fish – Black Scorpion Fish

Mediterranean Scaldfish

• Scientific name: Arnoglossus laterna
  
• Size: Up to 30cm
• UK shore caught record: N/a
• IUCN Status:
  • Global: LC (Least Concern)
  • Europe: LC (Least Concern)
• Distribution: Found throughout European waters.
• Feeds on: Marine invertebrates and other small creatures.
• Description: A thin-bodied flatfish which has an elongated oval body shape. Colour is usually light brown but can appear transparent, especially after the fish has been out of the water for some time. Some specimens may have darker patches or blotches on the body. The dorsal fin is longer than the anal fin and the lateral line has a distinctive curve to it.

The Mediterranean scaldfish is a small species of flatfish. Despite having a surprisingly wide distribution it remains an obscure species and is seldom caught on rod and line. As of 2020 there is no shore caught UK record for this species from shore or boat.

Distribution

As its name suggests the Mediterranean scaldfish can be found in the warmer waters of the Mediterranean Sea and surrounding waters. Its range extends from the colder waters of the Norwegian Sea all of the way along the coasts of the African continent. In UK waters it is predominantly found along the southern and western coasts of the British Isles but can turn up along the east coast of England and Scotland in smaller numbers.

Description, Size and Behaviour

The Mediterranean scaldfish is a small species, growing to a maximum of 30cm, with the average size being around half of this size. They mostly prefer sandy, muddy or shingle seabeds, although they can be found across mixed ground and only avoid heavy and rocky ground. While they will happily live at depths of several hundred metres they will also come into relatively shallow water of ten or fifteen metres, making it something of a mystery why this species has not been reported caught on rod and line and no British shore caught or boat caught record stands. Perhaps the rising popularity of LRF (Light Rock Fishing) will see this species begin to turn up in angler’s catches. Mediterranean scaldfish feed on small invertebrates, marine worms and any other small creatures which they come across on the seabed. They may also feed on very small fish species and the fry of larger species.

Commercial Value

Mediterranean scaldfish are edible, but have only a limited commercial value, probably due to their small size and the low amount of edible flesh they provide. Only small-scale artisan fishermen target this species, and it is available from fish markets and fishmongers in southern European countries. Larger scale fishing vessels are likely to discard any Mediterranean scaldfish they catch as unwanted bycatch. In some cases, this species may be retained for non-human consumption, such as being turned into fishmeal.

Rudderfish

• Scientific name: Centrolophus niger
  
• Also know as: Medusafish, Blackfish, Black Ruff
• Size: Grows to a maximum of around 3ft in length.
• UK shore caught record: 5lb 14oz
• IUCN Status
  • Global: LC (Least Concern)
  • Europe: LC (Least Concern)
• Distribution: Found worldwide in both warm and temperate seas.
• Feeds on: Opportunistic feeder eat prawns, small fish and squid.
• Description: Blunt snout with large, high head and relatively small mouth. High oval body with a long single dorsal fin which runs along two-thirds of the back and the anal fin is around one-third of body length. Colour usually dark grey to black, sometimes with a bluish or brownish tinge.

The rudderfish is a rare fish in UK waters. It is found predominantly in the Pacific, Atlantic and Mediterranean but is found in the waters of the British Isles with the places most likely to hold this species being to the west of Ireland, off the south-west coast of England and in the English Channel, and although specimens turn up elsewhere around the British Isles. Although immature rudderfish may be found in shallower water the fully grown rudderfish is a deeper water fish which lives and feeds in waters of around 100 to 200 metres deep all of the way down to over 1000 metres. This means that the rudderfish is a very rare catch indeed for shore anglers. This species is related to the similarly rare Cornish blackfish, as both species are in the Medusafish family.

The life cycle and feeding habits of rudderfish have not been well studied by science. It is thought that they can grow to at least three feet in length, possibly larger, and they feed opportunistically on small fish, squid, shrimps and prawns, although some accounts state that they can feed on some forms of plankton as well. Rudderfish are thought to feed higher up in the water column but may also scavenge on the seabed.

Despite its rarity this species does have a British shore caught record with S. Ostler catching a 5lb 14oz specimen from Aldbrough Beach, East Yorkshire in 1998. The boat caught record – a rudderfish of 3lb 10oz – was caught in Scottish waters in 1972. The International Game Fish Association website lists the all-tackle world record for this species as vacant, as of 2020.

Commercial Value

The rudderfish has limited commercial value. It is not targeted directly by commercial fisheries but may be retained when it is inadvertently caught in trawls. The largest market for this species is in Europe with Spain and Portugal being the main consumers of this species. When supplied for human consumption it is often marketed under the name black ruff or black ruff-fish.

Cornish Blackfish

• Scientific name: Schedophilus medusophagus
  
• Also know as: Portrush Barrelfish
• Size: Up to 3ft in length (but usually smaller than this).
• UK shore caught record: 8oz 4dr (233 grams)
• IUCN Status:
  • Global: NE (Not Evaluated)
  • Europe: LC (Least Concern)
• Distribution: Found to the south west of England and Ireland. Distribution also extends across the Atlantic to American and Canadian waters and is also present in the warmer waters around Europe.
• Feeds on: Thought to feed on jellyfish and small sea creatures.
• Description: Elongated oval body with a long dorsal fin which runs along the full length of the back. The anal fin is also long, approximately one third to half of the body length. Eyes are relatively large and located close to the snout, and lateral line curves upwards towards the gills. Colour usually black to brown, sometimes with mottled pattern.

The Cornish blackfish is a little understood and very rare species (in British waters) which, as its name suggests, is most commonly found to the south west of Britain and although populations may also be present in the English Channel. Smaller, immature Cornish blackfish may come into shallow waters but this is a deeper water fish once fully grown and is usually found at depths of around 300 to 1000 metres. The feeding habits of the Cornish blackfish are poorly understood, although it is confirmed that they consume jellyfish and similar creatures such as comb jellies, and may also take small crustaceans and invertebrates from the seabed. Practically nothing is known about the spawning or reproductive cycle of this species.

Name and Species Confusion

The Cornish blackfish is so-called as the first verified specimen came from the Cornish coast in 1859 and was given the scientific name Centrolophus brittanicus. However, in 1878 an immature specimen was caught from the Northern Irish coast at Portrush. As juvenile Cornish blackfish look siginifcantly different to mature specimens this fish was misidentified as a newly discovered species and was given the scientific name of Lirus medusophagus. The belief that these were two different species persisted into the twentieth century when it was eventually established that they were actually one species and were brought together under the scientific name of Schedophilus medusophagus.

The rudderfish Centrolophus niger (see above) is also sometimes referred to as blackfish. This species is also very rare in the waters around the British Isles and is a separate species to the Cornish blackfish.

Commercial Value and Scientific Interest

Cornish blackfish are occasionally caught in deep trawl nets which are targeting other species. As they have little commercial value and are classed as bycatch and are usually discarded back into the sea. Cornish blackfish is a rare catch indeed from either shore or boat. There is a UK shore caught record for this species with a specimen of 8 ounces and 4 drams (233 grams) caught by Mr R. Cooke on Cefn Sidan Beach, Carmarthenshire, Wales in 1983.

Bogue

• Scientific name: Boops boops
• Also known as: Bream
• Size: Up to 30cm and 2lbs
• UK shore caught record: 1lb 15oz
• IUCN status
  • Global: LC (Least Concern)
  • Europe: LC (Least Concern)
• Distribution: Common throughout the warmer waters of the Mediterranean and North Africa. At the edges of its distribution in British and Irish waters, but does turn up around the south coasts of Ireland, England and Wales in the summer months.
• Feeds on: Small crustaceans, prawns and shrimps, and can also feed on marine plants and seaweed, and have the ability to filter feed.
• Description: Small, slender fish. Eyes are relatively large and located close to snout. A single dorsal fin is present and the tail is deeply forked. Upper flanks are dark grey while the rest of the body is silvery. A number of dark golden stripes run along the length of the body.

The bogue is a small fish species that are found mostly throughout the warmer waters of Europe, especially the Mediterranean Sea, the Black Sea and in the warmer waters of the North East Atlantic. This species will live in shallow, inshore waters, but can also be found down in deeper waters of several hundred metres. They will feed on the seabed where they eat prawns, shrimps, marine worms and small crustaceans, and will also move up to mid-water to feed on the small mid-water crustaceans found there and during darkness they may come to the surface. Bogue will also eat plant matter such as seaweed and have a limited ability to filter feed on plankton through their gill rakers.

Bogue are of commercial importance with Mediterranean countries such as Spain and Greece accounting for the majority of commercial catches of this species. The FAO (Food and Agriculture Organisation of the United Nations) stating that around 35,000 tons of this species are caught in total every year, mostly by trawling or purse seining. The flesh is of good quality for human consumption but British fishermen catching bogue may discard catches at sea due to the lack of demand for this species in the UK. Bogue can also be used as a source of fish oil or fishmeal, or as live bait for commercial long lines which target tuna. Despite the relatively high levels of commercial exploitation bogue is classed as a species of Least Concern with a stable population in both European waters and on a global basis.

Despite being a rare fish there is a shore caught record for this species set in 1978 by S.G. Torode who caught a bogue weighing 1lb 15oz while fishing in Guernsey, Channel Islands. The boat caught record is a fish of 1lb 13oz caught by K. McBride off Eddystone Reef off the coast of South West England in 1981.

Blue Runner

• • Scientific name: Caranx crysos
    
  • Also know as: Hardtail, Hardtailed Jack, Hardnose, Bluestripe, Blue Jack, Green Jack, Blue Mackerel, Egyptian Scad, Cavalli, Yellowtail Cavalli, Yellow Mackerel
  • Size: Up to 3ft and 10lbs, although typically around 1ft and 2lbs
  • UK shore caught record: 2lb 8oz
  • IGFA all-tackle world record: 11lb 2oz
  • IUCN status
    • Global: LC (Least Concern)
    • Europe: LC (Least Concern)
  • Distribution: A species widespread throughout tropical and temperate waters, but the range of this species appears to be extending northwards.
  • Feeds on: Small predator which feeds by hunting small fish. Occasionally other food sources such as crabs and prawns.
  • Description: Small, fast-swimming fish which is similar in profile to a tuna. The first dorsal fin is triangular and small, while the second dorsal fin is long and runs down to the tailfin. The anal fin is similar in size. Pectoral fin is long while pelvic fins are short. The tail is long and deeply forked. The mouth has small, sharp teeth and eyes are large. Colour is usually bluish to green, fading to pale, sometimes silver on the underside. A black mark is often present on the gills and points of the tail are also sometimes tipped with black.

The blue runner is a fast, swimming predatory fish which is abundant throughout many temperate and tropical waters throughout the world. Once considered absent from UK waters this species does appear to be extending its distribution northwards and is being observed off the south west coast of England, possibly as a result of warming sea temperatures caused by global warming.

Distribution

In European waters the blue runner is found throughout the Mediterranean and off the coasts of Portugal, France and Spain. It is also present along much of the west coast of Africa. It is also found off the eastern coast of North America, through the Caribbean Sea and the Gulf of Mexico and along the eastern coastline of South America.

Life Cycle and Feeding

The blue runner is a shoaling fish which behaves in a similar manner to small tuna species (such as skipjack). Large numbers of blue runner will join together to feed on any small preyfish they can hunt down. They are generally seen as a pelagic fish and hunt in mid-water on smaller fish, which means in British waters they will be most likely to feed on mackerel, herring and sandeels but they will occasionally feed on the seabed if food, such as prawns, is present there. Blue runner is not a deep water species and are generally found in water less than one hundred metres deep. Blue runner are known to be attracted to both natural reefs and man-made structures such as oil platforms artificial reefs, and will often be found shoaling around these structures.

Blue runner spawns anytime from the early spring to the late summer, with females releasing eggs which hatch into small plankton-feeding larva. Once fully formed the small fish will live in shallower water, moving into slightly deeper water once they reach around 20 – 30cm in length.

Commercial and Recreational Fishing

The blue runner is edible and in some parts of the world this species makes up the main catch of small-scale fisheries, creating a source of both food and employment. Commercially the blue runner is caught in a variety of methods such as purse seining, trawling, gill nets and on long lines. The blue runner is thought to be abundant and is classed under the category of Least Concern by the IUCN (International Union for the Conservation of Nature) in both European waters and globally. In recreational fishing terms, the blue runner is seen as an excellent sportfish due to its fast-swimming nature and powerful runs, especially when using light tackle. They are usually caught on artificial lures such as jigs and spinners. Due to the great fighting qualities of the blue runner, many UK based anglers will be happy to see this species becoming more common around the British Isles and would welcome the opportunity to catch this species.

Record Catches

The UK shore caught record is a specimen of 2lb 8oz, caught by Nick Rodgers off the Cornish coast in 2007. No British boat caught record is currently listed. The International Game Fish Association all-tackle world record for this species is 11lb 2oz. This blue runner was caught by Ms. Stacey Moiren at Dauphin Island, Alabama, USA in 1997.

Long Rough Dab

• Scientific name: Hippoglossoides platessoides
• Also known as: American Plaice, American Sole, Rough Dab
• Size: Up to 50cm in length. Typically half this size.
• UK shore caught record: 5oz 8dr (155 grams)
• IUCN Status
  • Global: NE (Not Evaluated)
  • Europe: LC (Least Concern)
• Distribution: Found throughout the North East Atlantic with separate populations in European waters and off the eastern coast of North America.
• Feeds on: Marine worms, invertebrates and small crustaceans and small fish.
• Description: Oval and somewhat elongated body. Eyes are on the right with dorsal fin starting level with the eyes. The colour is usually brown with black/dark spots. The skin is rough to the touch and the mouth is relatively large. The lateral line is nearly straight with only a slight curve towards the gills.

Long rough dab are often classed as a mini-species as the specimens caught in UK waters are small – the shore caught record is just over five ounces. This species can in fact grow to over 10lbs in weight, although specimens of this size are rare as they are usually caught long before they can reach these sizes. They are caught much more often from the coast of countries such as Iceland and Scandinavian countries and, as an edible species, are a highly important commercial fish in the United States of America and in Canada. This species has a relatively low profile in the British Isles and is mostly unknown to both UK anglers and consumers.

Distribution and Species Differences

Long rough dab are a species which is endemic to the North Atlantic. They prefer cooler waters and on the European side of their distribution, they are found throughout the Norwegian Sea, the Baltic Sea and the North Sea, as well as around the coast of Iceland and Greenland. They are found in the English Channel but are absent from the coastline of Spain, Portugal and the Mediterranean Sea. Their range continues across the Atlantic and they are found off the coast of Nova Scotia and down to Massachusetts. Long rough dab from different regions may have genetic differences and there are a number of sub-species recognised.

Habitat, Feeding and Reproduction

Long rough dab live over clean muddy and sandy bottoms in water as shallow as ten metres, but are usually found in water much deeper than this, sometimes down as deep as four hundred metres. Long rough dab generally feed on marine worms, invertebrates, brittle stars and molluscs. As they get older and bigger they add fish to this and hunt for sprats, sandeels and capelin. When living in warmer climates towards the American edge of their distribution long rough dab are thought to be able to reproduce are three years old and around 30cm in length. In colder Scandinavian waters around Europe they may need reach an older age (possibly as old as seven or eight years) and a larger size before reproduction can happen. Spawning generally takes place in the spring months.

Commercial Value

Long rough dab are a commercially important species and are caught by trawling or static nets. On the North American side of the Atlantic this species was heavily overfished in from the late 1960s until well into the 1990s, severely deleting stocks – a situation made worse by disagreements and political wrangling. The USA’s Northwest Atlantic Fisheries Organization has considered this species to be subject to overfishing stated that stocks were in serious trouble, whereas the Canadian government believed this species was abundant continued to fish for it at a high intensity.

It is now accepted that all stocks of long rough dab are depleted and a number of moratoriums and bycatch reduction schemes are in place throughout North American waters in an attempt to allow a stock recovery to take place. In Europe, the long rough dab is not as commercially valuable and fished for at a much lower intensity. The International Union for the Conservation of Nature classes them as a species of Least Concern in the European assessment area.

Seafish – the UK taxpayer funded quango which represents the UK commercial fishing industry – states that due to being a separate species to European plaice (Pleuronectes platessa) long rough dab should not be marketed under the plaice name in the United Kingdom.

Sand Sole

• Scientific name: Pegusa lascaris
• Size: Up to 40cm and 3lbs
• UK minimum size: N/a
• UK shore caught record: No record listed.
• IUCN status: NE (Not Evaluated)
• Distribution: UK distribution is limited to the southern coasts of the England and Wales and the southern waters of Ireland. Distribution extends to parts of the Atlantic and the Mediterranean Sea.
• Feeds on: Small marine creatures such as prawns and worms.
• Description: Right-sided flatfish with a similar shape to a Dover sole. Colour is usually a light speckled brown. Fins continue around most of body and tail fin is very small and rounded. A distinctive rosette-shaped nostril is present on the underside of this species.

The sand sole is a smallish species of flatfish which is mostly found around the southern coast of the British Isles. It appears to be rarely caught on rod and line – although it is possibly caught more often than realised and misidentified as a Dover sole. It is of little interest to UK commercial fishermen, but is caught and sold in fisheries elsewhere in Europe.

Distribution

British distribution runs from the southern North Sea around East Anglia to the southern parts of the Welsh coastline, while it can also be found around the coast of the Republic of Ireland. There are also populations of this species in various parts of the Atlantic and in the waters around the western Mediterranean sea, although its range does not extend to the Black Sea. Also found all along the west coast of Africa, as far as the waters of South Africa.

Habitat and Feeding

The sand sole can – as its name implies – be found on sandy seabeds, although it can also be found over shingle and muddy seabeds as it only avoids rocky areas. It generally grows to around 20 – 30cm in length, although in some cases it can grow to around 40cm and several pounds in weight. This species is generally found in relatively shallow water down to around thirty metres deep, although in some areas they may be found as deep as several hundred metres. Like most flatfish species it is an opportunistic feeder, taking small marine creatures such as sea slaters, prawns, dislodged shellfish and marine worms, although it may also scavenge on dead fish. Sand sole are thought to be able to live for up to ten years.

Angling and Commercial Value.

While sand sole is a rare species around much of the UK it may be the case that this species are caught more often than realised, but misidentified as another flatfish species such as Dover sole or lemon sole. There are few verified reports of this species being caught on rod and line and no UK shore caught record is currently recorded (but this may be down to the misidentification issues). The sand sole is a commercially important species in much of Europe. Although the International Union for the Conservation of Nature state that this species is one of Least Concern they highlight the fishing intensity stocks are under in the Mediterranean as a potential threat.

Red Scorpion Fish

• Scientific name: Scorpaena scrofa
  
• Also know as: Big-scale Scorpion Fish, Large-scale scorpion fish, Rascasse, Red Rascasse
• Size: Up to 60cm in length, but usually half this size or smaller.
• UK minimum size: 8ins / 20cm
• UK shore caught record: No record currently listed.
• IUCN Status: LC (Least Concern)
• Distribution: Found along the western coast of Africa and throughout the Mediterranean. At the northern edge of its distribution in British waters but can be found off the coast of south west England and in the English Channel.
• Feeds on: Mostly other fish but will scavenge for other food sources.
• Description: Small to medium-sized squat fish, with a fatty, broad body. The colour is usually orange with darker mottled spots and patches and is covered in lumps and protrusions. Pectoral fins are broad and almost circular, first dorsal fin has a number of spines which secrete venom, as do the gill covers.
• Additional notes: Not be confused with the long-spined and short-spined scorpion fish.

The red scorpion fish is a species which is rare in UK waters, but it is found off the coast of southern and western England. It generally prefers deeper offshore waters at least thirty metres deep and can be found all of the way down to several hundred metres. This preference for deeper water, and its feeding method as an ambush predator perhaps explains why it is not often encountered by UK anglers, although they are occasionally inadvertently caught by commercial vessels in the waters of the British Isles.

Appearance, Habitat and Feeding

A striking looking fish with a fat body, often covered in lumps and bumps, this species has venomous spines on its back and gill covers. It is a solitary species, gathering with other red scorpion fish only to spawn, although very little is known about the reproduction patterns of this species. Red scorpion fish are usually found in rocky and broken offshore grounds. They are nocturnal, hiding away in cracks and crevices between the rocks during daylight hours and emerging at night to hunt. They work as an ambush predator, lying in wait until a small fish or prawn comes within striking range when they will dart out and catch the creature in their jaws. They are also thought to scavenge on dead fish or shellfish they may come across.

Human Interactions and Commercial Value

Due to the venom this species has they are a threat to divers and commercial fishermen who may handle this species. The effect of the venom is said to be more powerful than that of the weever fish and can cause intense pain, headaches and vomiting. In extreme cases, people stung by this species can require hospital treatment. Despite this, the red scorpionfish is commercially important in the Mediterranean and is the traditional fish to use in bouillabaisse, a French dish which originates from the port city of Marseilles. In the Mediterranean this species is caught using small-scale trawls, gill nets and tangle nets. In other parts of the world where this species is present it may be caught as bycatch and discarded at sea. Despite the commercial attention this species receives it is classed as a species of Least Concern with a stable population trend by the International Union for the Conservation of Nature in all of the areas where it has been assessed. However, the IUCN recommend that this species is monitored as its long lifespan, relatively slow growth and lack of mobility mean that numbers could be reduced by overfishing in the future.

Black Scorpion Fish

• Scientific name: Scorpaena porcus
• Also know as: Small-scale scorpion fish
• Size: Up to 40cm in length but often no more than 15 – 20cm
• UK minimum size: 8ins / 20cm
• UK shore caught record: No record currently listed.
• IUCN Status: LC (Least Concern)
• Distribution: Found through the Mediterranean, Black Sea and north coast of Africa. Also found along the Atlantic coast of Spain, France and Portugal. Rare in UK waters but observed off the coasts of Cornwall, Wales, and parts of Ireland and in the English Channel. Also found in Irish waters.
• Feeds on: Small fish and prawns and will also scavenge any other food sources.
• Description:
• Usually mottled dark brown/light brown in colour, sometimes with black or grey patches. Skin is covered with lumps and protrusions. The pectoral fins are broad and near-circular and the dorsal fins have venomous spines.
• Additional notes: Not be confused with sea scorpion species.

The black scorpion fish is distinguished from the red scorpion fish by its smaller size and darker colour. This species is much more common in the Mediterranean and the Black Sea, but can occasionally be found along the southern and western coasts of the British Isles. This species of scorpion fish is also generally found in rocky offshore waters, but may come into shallower water than the red scorpion fish and may also live across seabeds with less rock and weed cover. This species is also solitary and also preys on smaller species of fish as an ambush predator.

This species is commercially valuable and is mostly caught in the Mediterranean. The ICUN (International Union for the Conservation of Nature) lists it as a species of Least Concern in this area, as well as in the European region and globally, although they point out that the continued effects of overfishing and pollution may mean that the status of the black scorpion fish will need to be reassessed in the future as numbers could decline.