Cyclopterus lumpus Linnaeus, 1758

Sexual Dimorphism Overview

Cyclopterus lumpus displays sexual dimorphism, with females growing larger than males.

Male Typical Size

Males typically reach 30 to 40 cm (12 to 16 in) in length, while females usually grow up to 50 cm (20 in) in length and 5 kg (11 lb 0 oz) in weight.

Record Maximum Size

The largest recorded specimen measured 61 cm (24 in) in length and 9.6 kg (21 lb 3 oz) in weight.

Baltic Sea Population Size

In the brackish water of the Baltic Sea, this species usually does not grow larger than 20 cm (8 in).

Body Shape and Tubercles

It has a ball-shaped body, a knobbly, ridged back, and three large bony tubercles on each flank.

Pelvic Fin Adaptation

Its pelvic fins form suction discs that it uses to attach strongly to rocks or other surfaces.

Sexually Dimorphic Morphology

Males have larger heads and pectoral fins than females.

Subcutaneous Fat Layer

There is a jelly-like layer of fat under the skin.

Base Coloration

Its colour is highly variable, and can be bluish, greyish, olive, yellowish or brownish.

Breeding Season Male Coloration

Mature males turn orange-reddish during the breeding season.

Roe Nutritional Content

The roe of Cyclopterus lumpus is a good source of omega-3 fatty acids, and is used to make relatively inexpensive caviar substitutes.

Initial Roe Processing

After being removed from the fish, the roe is processed to remove connective tissue, then stored in large barrels and salted.

Final Roe Preparation

It is dyed either red or black, and packed with a mould inhibitor such as sodium benzoate (E211).

Scandinavian Culinary Use

In Scandinavia, the flesh of this fish is eaten.

Icelandic Male Preparation Methods

In Iceland, males are often salted and smoked, or simply boiled.

Icelandic Female Preparation Process

Female lumpfish are rarely eaten fresh, but when caught during the spawning season, their guts and heads are removed, the flesh is deeply scored with a knife, and they are hung in a cool place until the flesh turns yellow.

Traditional Icelandic Dish

The fish is then poached before serving as the Icelandic dish called sigin grásleppa.

Aquaculture Use

This species is also used as "cleaner fish" to lower parasite burdens on salmon farms in Scotland, Iceland and Norway.