Latin name

Channichthys rugosus

Other name

Channichthys rugosus

Identification

Red icefish is distinguished from other species of the genus Channichthys by the following set of characters. In the dorsal (upper) lateral line 57-82 tubular bony segments (scales), in the posterior part of the medial (middle) lateral line 7-23 tubular bony segments (scales), in the anterior part - medial line 3-30 rounded dense punctate bony plaques; in the lower part of the gill arch 7-14 stamens located only in the outer row; vertebrae 54-56, of which 22-24 trunk and 32-33 caudal. Eye small (15-18% of head length or 30-36% of snout length). The interorbital space is narrow (11-14% of head length), smaller than the diameter of the orbit, concave, with the outer edges of the frontal bones distinctly raised above the orbit. The posterior edge of the jawbone extends posteriorly to a vertical line through the centre of the orbit. Granulation (tuberculation) is generally moderate, except on the top of the head, where flattened and spiny small bony granules densely cover the frontal bones; may be present on the pelvic fin rays and gill rays; absent on the upper jaw and in the anterior part of the lower jaw. As in other predatory relatives of the red icefish, the gill stamens are few and arranged in a single row on the lower part of the first gill arch.

The red icefish has a well-developed rostral spike ("horn") at the front of its snout. It is characterised by the absence of scales on the body (except for the lateral lines) and by the possession of a unique phenomenon among all vertebrates, peculiar to only 25 species of fish in this family - the presence of "white" blood, a slightly yellowish plasma devoid of red blood cells and haemoglobin. This phenomenon is explained by the adaptation of ancestral forms of white-blooded fish to the harsh conditions of the Antarctic and the negative water temperature of the Southern Ocean, close to freezing point (-1.9°C).

Features of fish fins

The first dorsal fin has 8-11 flexible barb rays (more often 9-10), of which the largest rays are from the 3rd to the 5th (more often 3-4); the second dorsal fin has 31-34 rays; the anal fin has 29-31 rays; the pectoral fin has 18-29 rays, more often 19 rays (the smallest number of rays in the genus).

The first dorsal fin is very high, 3.2-3.8 times the standard length of the fish, trapezoidal in shape, with a high fin fold reaching the tips of the flexible barb rays. The first and second dorsal fins are in contact with their bases or separated by a narrow interdorsal gap. 

Fish colouring

The general colouration of the fish usually varies from yellowish orange and pale pink to bright reddish or brownish ochre. The sides of the body are uniformly covered with melanophores, without pronounced dark patches or transverse stripes. The underside of the head, chest and parts of the body adjacent to the anal fin are pale; some fish have fairly large dark or brownish spots on the chest and abdomen and small bright orange spots up to 2-4 mm in diameter. The first dorsal fin is black with light rays. The rays of the pectoral, caudal and second dorsal fins are grey or dark grey, the fin pleats are pale. The anal fin is pale at the base and slightly darker in the lower half. In the pelvic fins, the rays are pale and the folds dark. In fish fixed in formalin or alcohol, the general colouration of the body changes to light grey or brownish-brown.

Distribution

It is endemic to the Indian Ocean waters around the islands of the Kerguelen Archipelago in the Indian Ocean sector of the Subantarctic. It is also thought to inhabit a number of underwater elevations - gaiotes (cans) - in the area of the Kerguelen submarine ridge, as well as Hird and McDonald Islands, which lie at the southern end of the Kerguelen submarine ridge.

Habitat

Polar shallow-water demersal species recorded at depths of 112-250 m.

Size

It belongs to the group of small species of the genus Channichthys. The largest females reach a total length of 311 mm and a standard length of 280 mm.

Behavior

A bottom dweller. It is found in bottom areas with thickets of brown algae and a significant amount of echinoderms and glass sponges. 

Food and feeding habits

An ichthyophagous and benthophagous predator that appears to feed on the bottom surface. 

Reproduction

Females do not reach sexual maturity until they are about 24-28 cm long (22-25 cm standard length). Spawning appears to occur in summer or autumn in the southern hemisphere.

Fishing

May occur as by-catch in the Kerguelen Islands Chamsocephalus gunnari Lönnberg, 1905.

Relationship with a person

Harmless.