Thymallus - Two species of the genus Thymallidae. Freshwater river and lake fish. They have teeth on the jaws, scolex, on the palate and sometimes on the tongue, a long and high dorsal fin. Thymallus thymallus lives in the waters of Europe, there is no it in the Caucasus and the Crimea. It reaches 50 cm in length and weighs up to 1 kg. It reaches sexual maturity in 2-3 years, in the north in 7 years. Spawns in May-June. It lays its bottom eggs on sandy bottoms on the waves. Fecundity from 3 to 36 thousand eggs. It feeds on molluscs, aquatic insect larvae, insects that fall into the water, young fish and eggs. Thymallus arcticus lives in Siberian rivers from the Kara River to Kamchatka. It forms numerous subspecies of West and East Siberian, Amur, Baikal (white and black) Thymallus. It has a large mouth compared to the European, the teeth on the jaws are very prominent. It has a body length of 50 cm or more. It matures at the age of 3-5 years. Fecundity of 5-10 thousand eggs. Spawns in spring in a fast current. It feeds on aquatic invertebrates, larvae and adult insects, sometimes on fish. Thymallus is an object of local and sport fishing.

A characteristic feature is a large dorsal fin, the posterior part of which, when folded in mature males, reaches the adipose and sometimes the base of the caudal fins. Thymallus has one of the most beautiful colours of any Holarctic reservoir fish. The fish has a monotonous dark grey back, on the sides of the body of some species scattered black spots of various shapes. Siberian, Baikal, Amur, Lower Amur and yellow-spotted thymallus have a relatively large reddish spot above the pelvic fins. The pelvic fins have oblique reddish-brown stripes with a purplish tinge. The caudal and anal fins of adults are red-burgundy. The posterior part of the dorsal fin of males is higher than the anterior part. In females this part of the fin is smaller or of the same height. Several horizontal rows of reddish spots are clearly visible, ranging from rounded to long vertical stripes of turquoise or purple hues. The largest individuals (up to 5-6 kg) are found in Mongolian and European Thymallus. Dwarf forms are also known from the high mountain lakes of Siberia, which retain their fry colouration in the form of dark transverse stripes on the sides of the body throughout their lives.