Common Blenny


  • Scientific name: Lipophrys pholis
  • Also know as: Shanny, Smooth Blenny, Sea Frog
  • Size: Up to 20cm
  • UK minimum size: 20cm
  • UK shore caught record: 112 grams
  • IUCN Status: NE (Not Evaluated)
  • Distribution: Common around all of the British Isles. Also found in other European waters.
  • Feeds on: Marine invertebrates and worms.
  • Description: Small fish with a smooth, slimy body which appears to be scaleless. A dorsal fin runs the full length of the back and has a noticeable notch in the middle, the anal fin is also long and the tail small. Eyes located high up on the head and no sensory organs are present. Colour can vary from fish to fish, but is usually dark brownish to grey, although males change colour in the breeding season.

The common blenny is a small shallow-water fish which is commonly found in coastal, inshore waters all around the UK and is often encountered by people exploring rock pools at low tide. Being a member of the Blenniidae family it is a true blenny species (although it goes under a range of other names, most often shanny). The common blenny is abundant around the British Isles although it is found elsewhere in European waters, such as the western Mediterranean Sea. Being a shallow water fish which the common blenny will spend its whole life living in the inter-tidal zone of rocky coastlines. When the tide is in the common blenny will search for sources of food such as small prawns, sea slaters, ragworms, lugworms and any other small creatures which are found in inshore waters. When the tide goes out common blennies will remain in the same area and take refuge in a rockpool until the tide comes back in.

However, if the common blenny cannot locate a rockpool it will instead hide in a crack or crevice or under a rock or within a weed bed. Provided the environment is damp and moist and contains weed cover this species is capable of living out of water for many hours. Indeed, common blennies can sometimes be observed completely out of the water, making their way across seaweed or between rocks, with this amphibious behaviour leading to the shanny being given the alternative name of the sea frog. Male common blennies usually change colour in the spring/summer breeding season, and females will lay eggs under rocks in the intertidal zone. Males will stay near to the eggs to guard them until they hatch. Common blenny can live for at least ten years, and it is thought that this species may be able to live for as long as 15 – 20 years.

Common Blenny LRF
A common blenny caught on LRF tackle.

Very much a mini species the common blenny has a British shore caught record of 112 grams (3oz 15dr) caught by M. Carter, Poldhu Cove, near The Lizard, Cornwall in 1995. The common blenny is becoming an increasingly popular species for anglers to catch, with the growth of LRF (Light Rock Fishing). The range of other blenny species which are found in British waters can be viewed on this page.