:: Antarctic Teleost Icefish ::

The fishes of the family of Channichthyidae, commonly called icefishes (ice fish) or icefishes crocodile (alligator ice fish), are saltwater fish belonging to the order Nototenioidea. They are among the few fish that live in Antarctic waters.

They have an elongated body that is refined towards the tail. The head is large with a pointed snout and large eyes. The pectoral fins are well developed, ventral fins are long and stiff (often used as a support to lean on the bottom) the anal fin is thin and barely visible, the tail broad and muscular. On the back have two dorsal fins, the first developed with strong rays. The lack cannictidi swim bladder.

These fish can survive in Antarctic waters, whose temperature ranges between -1 and -2 ° C, since their blood has a low viscosity. To reduce the viscosity of blood (which would involve a greater expenditure of energy for the body) the cannictidi have evolved eliminating the red blood cells and hemoglobin, which, taking advantage of the fact that in water at low temperature oxygen is much more soluble and tends to be absorbed by the blood gills with more ease. 

Additionally implement these fish breathing skin: have a dense network of capillaries near the skin, devoid of scales, which can then be further gas exchange with the environment. Fertilization is external, the eggs (yellow-orange, 2-3 mm in diameter) are fertilized at the time of deposition.

scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Perciformes
Suborder: Nototenioidea
Family: Channichthyidae