Cyclopterus is sexually dimorphic with females reaching larger sizes than the males. Males typically reach 30–40 cm (12–16 in) in length while females can typically grow up to 50 cm (20 in) in length and 5 kg (11 lb 0 oz) in weight. The largest specimen recorded measured 61 cm (24 in) in length, and 9.6 kg (21 lb 3 oz) in weight. In the brackish water of the Baltic Sea, it usually does not surpass 20 cm (8 in). The body is ball-like. It has a knobbly, ridged back and three large bony tubercles on each flank. Its pelvic fins form suction discs which it uses to attach strongly to rocks or other surfaces. The head and the pectoral fins of males are larger than those of females. It has a jelly-like layer of fat under the skin. Its colour is highly variable; bluish, greyish, olive, yellowish or brownish. Mature males turn orange-reddish during the breeding season.









































































































































































































































































































































































































































































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