Blenny is a wide-ranging – and at times confusing – classification of fish species which are found around the British Isles. Blennies are small fish which live in shallow, sheltered inshore waters and are usually classed as a mini species by UK anglers. Most blenny species can be distinguished by their single dorsal fin, which runs the full length of the body and has a distinctive notch in the centre which can make it look like two separate fins. However, a number of related species (which are not members of the Blenniidae family) are often commonly referred to as blennies by anglers and are therefore included on this page.

The more common species such as the tompot blenny and common blenny (also known as the shanny) have their own profiles on this site, as do species which sometimes have the blenny name applied to them such as the eelpout (which is also known as the Viviparous Blenny).

While the minor blenny species were previously ignored by anglers the growing popularity of LRF (Light Rock Fishing) means that an increasing number of anglers are catching blenny species and looking to identify the fish which they have caught. Due to their small size and the fact that they are not edible blenny species are of no commercial interest and their inshore habitat protects them from being caught as bycatch. All of the species on this page are believed to have stable populations and there are no major threats to any of the species.

The following species are listed below. Click on a species to jump to that section, or scroll down to read the entry on each species

Yarrell’s Blenny – Portuguese Blenny – Montagu’s Blenny – Butterfly Blenny – Black Faced Blenny

Yarrell’s Blenny

• Scientific name: Chirolophis ascanii
• UK Shore Caught Record: 86 grams

A relatively large species which can grow to lengths over 20cm, this fish is a member of the Stichaeidae family. A high dorsal fin, which is uniform in height, runs along the entire length of the back, and the anal fin runs for approximately two-thirds of the body length. The tail fin and pectoral fins are rounded and the colour is often a mottled greeny-yellow, although this can vary to reddish, brownish or orange. A dark line runs down the eye and small tentacles are present above the eyes.

Yarrell’s blenny is all around the British Isles, although it is slightly more common around the north. Its range extends into Scandinavian waters and it is also found in the Baltic Sea. Some reports state that this species is also present in the waters of Iceland and Greenland and on the eastern coast of Canada. Yarrell’s blenny generally favour rockier areas with weed cover and tend to avoid the inter-tidal zone and seek out slightly deeper water. They feed on marine worms, sea slaters, prawns shrimps and other small creatures. The shore caught record, a specimen of 86 grams was caught in 1996 by D. Owen off Raven’s Point, North Wales. This species is named after William Yarrell, the British zoologist and naturalist (1784 – 1856) who wrote the influential book A History of British Fishes in 1836.

Portuguese Blenny

• Scientific name: Parablennius ruber
• Also known as: Red Blenny
• UK Shore Caught Record: No record listed

The Portuguese blenny grows to around 15cm in length. It has large pectoral fins and a dorsal fin which runs the full length of the back with the anal fin running for approximately half the body length. The caudal (tail) fin is square-shaped. Eyes are prominent with several fringed tentacles on the head and the mouth is small. Colour can be a vivid red with darker and lighter bars and blotches present on the flanks, although they can also be a duller brown or orange.

This species was previously thought to only be present in Portuguese waters (hence the name) but it is now apparent that it has a much wider distribution than first realised and is found in British and Irish waters. It now appears that Portuguese blennies which were found in British and Irish waters were confused with the closely related tompot blenny (Parablennius gattorugine) for many years, with the two species only being differentiated in the early 1980s.

Portuguese blenny live in shallow, rocky waters which have weeds present, and avoid deeper offshore waters. They can often be spotted in the inter-tidal zone and will sometimes become trapped in rock pools by the outgoing tide. Portuguese blenny feed on marine worms and sea slaters, as well as small prawns and shrimps. There is currently no shore caught record listed for this species, although it is possible that record-qualifying Portuguese blennies have been caught and misidentified as tompot blennies.

Montagu’s Blenny

• Scientific name: Coryphoblennius galerita
• UK Shore Caught Record: No record listed

This species of blenny has an elongated body and grows to a maximum of 8 – 9cm in length. What looks like two dorsal fins are actually joined in the middle and the anal fin runs for one-third of the total body length. Pectoral fins are relatively large and round. Colour is usually a light brown to pale yellow with darker bars running along the flanks, while white or light blue spots can also be present. A single frilled protuberance is present behind the eyes.

Montagu’s blenny generally favour slightly warmer waters than those found around the UK, meaning it is common in the Mediterranean, the Black Sea and the North East Atlantic. In British and Irish waters it is much more common along the south west coast of England, parts of the English Channel, the Welsh coast and the southern coast of Ireland, although it can turn up further north in smaller numbers. This species lives in very shallow water around rocky and broken ground and can often be found in the inter-tidal zone. Like the common blenny it can survive for a long time out of the water and can sometimes be observed on rocks completely out of the water. Montagu’s blenny feeds on tiny marine crustaceans and marine worms and also consumes algae and marine vegetation. There is currently no shore caught record listed for this species.

Butterfly Blenny

• Scientific name: Blennius ocellaris
• UK Shore Caught Record: 35 grams

A striking looking blenny species which can grow to a maximum length of around 20cm. This species is instantly recognisable by its very high dorsal fin which has prominent spined rays and a conspicuous black spot in the centre. Pectoral fins are large and tail is rounded. Frilled protuberances are present on the head above the eyes. Colour is usually light brown with darker bars or blotches on the flanks, although colour can be tinged with blue, purple or red. This species is found in the warmer water of the Mediterranean, although it can also be found in the Black Sea, and along the northern coast of Africa and along the Atlantic coastline of Spain, France and in Portuguese waters. In Britain and Ireland it is usually found around the southern coastline but has been observed further northwards in smaller numbers.

This species tends to favour slightly deeper waters of at least several metres and avoids the inter-tidal zone. It is usually found over harder seabeds and feeds on all manner of small marine creatures such as marine worms, shrimps, prawns and sea slaters. The shore caught record for this species was set in 2003 when Cliff Williams caught a specimen weighing 35 grams off the coast of Weymouth in Dorset.

Black Faced Blenny

• Scientific name: Tripterygion delaisi
• UK Shore Caught Record: 2.95 grams

The black faced blenny has three dorsal fins, the first of which is very small and the second and third are longer and triangular. The colour of this species can vary greatly. The females are a dull mottled brown colour, whereas the males are similar for most of the year, but change colour drastically in the breeding season, becoming a bright yellow, with a jet black head and the fins becoming lined with blue – the picture above shows a breeding season male in the foreground with a female behind. This has caused confusion as it was once believed that the male in its breeding colours was a separate species. Further confusion is caused because outside of its breeding season this species does not have a black face.

Like most blenny species the black faced blenny is found across rocky and broken seabeds in shallow water and within the inter-tidal zone. It is most common off the coastline of Spain, France and Portugal, in the Mediterenean Sea and off the northern coast of Africa, but it can be found in the English Channel and off the coast of the south west of England and west coast of Ireland, as well as further north along the coastline of the British Isles in much more limited numbers.

They feed on small marine invertebrates and crustaceans such as shrimps and sea slaters and will also eat marine worms. When in its breeding colours the male will swim in a figure of eight pattern to attract the female which will then lay the eggs which the male will guard and act territorially to protect. A Spanish academic study, published in 2014, stated that some males do not change colour and ‘sneak breed’ by waiting until the female has laid eggs and then fertilising them before other males have been able to.

The shore caught record for the black faced blenny was set in 2014 when Nina Frapple caught a specimen weighing 2.95 grams. Like the butterfly blenny, this was also caught off the coast of Weymouth, Dorset and is one of the UK’s smallest records for a shore caught fish.