Common Lumpsucker

The Common Lumpsucker (Cyclopterus lumpus) is the sole member of its genus in the family Cyclopteridae, found across the North Atlantic from the eastern coast of North America to Europe and into the Arctic. Its rounded, scaleless body and modified pelvic fins fused into a ventral sucking disc make it one of the most distinctive fish shapes in northern waters. Adults spend much of the year in open water before moving inshore to spawn on rocky shores, where males guard the eggs. The species shows strong sexual dimorphism, with females growing considerably larger and bulkier than males. It is not currently considered globally threatened, though some regional stocks are monitored.

Identify the Common Lumpsucker by:

• Rounded, ball-like or tadpole-shaped body, unusual among fish
• Thick, rubbery, scaleless skin studded with rows of bony tubercles
• Coloration ranging from blue-grey and greenish to reddish-brown, often duller in males
• A modified sucker disc on the underside formed from fused pelvic fins
• Small dorsal and anal fins set far back on the body
• Adult females noticeably larger and rounder than males

Its globular body shape and adhesive disc make it difficult to confuse with any other North Atlantic fish.

Common Lumpsucker ranges throughout the North Atlantic, from the Gulf of Maine and Labrador in the west to the Barents Sea, Iceland, and the coasts of Europe in the east. Adults are largely pelagic for much of the year, drifting in open, cold water often associated with drifting seaweed, while during the breeding season they move into shallow rocky intertidal and subtidal zones to spawn. Depth range varies seasonally from the shoreline down to several hundred meters offshore. It favors cold, temperate to subarctic water temperatures typical of northern seas.

Common Lumpsuckers are generally solitary and slow-moving, relying on their rounded body and camouflage coloration rather than speed to avoid predators. Using its ventral sucker disc, formed from fused pelvic fins, it can attach firmly to rocks or other surfaces to hold position in strong currents. During the breeding season, females deposit large clumps of eggs on rocky substrate in shallow water, after which males take on sole responsibility for guarding and aerating the egg mass until hatching, a period of dedicated parental care unusual among fish. Outside the breeding season, adults disperse into open water to feed on small crustaceans, jellyfish, and other invertebrates.