The Lake Frog is big (the body of the male is up to 12 cm, female 14 cm long). Its back is green, either olive-green or dark brown, with black or dark patches. Ventral side is greyish or yellowish with black spots.
The life of the frog is closely connected with water. It leads its whole life in water leaving for mainland only in damp and warm weather. It prefers larger lakes with rich vegetation or quiet river bends.
Although it stays most of the time in water, it feeds in the plants near the body of the water. It mainly feeds on insects and crustaceans but occasionally it eats fry, tadpoles, shrews, and the young of water birds. Yet vertebrates are not an important part of its food. The frog either stays without moving at the surface of water or swim lazily. The Lake Frog is active both in the day-time and at night but in spite of it we cannot see it very often. It is a very cautious animal and hides itself hearing any noise made by a man.
The Lake Frog spends hibernation time in the mud of the body of the water. They begin to reproduce either a couple of weeks or a month after hibernation. The male frogs are very lively and sing in chorus in a hoarse voice. In order to sing louder dark acoustic bladders appear at the corners of the mouth. The period of spawning is long and the female frog lays up to 3,000 eggs into the depth of 5 to 10 cm. The eggs are laid either once or several times. The frog likes warmth and the temperature for spawning has to be 15 - 18 C.
The development of tadpoles is long, it lasts 80 - 90 days. Light yellow or brown tadpoles turn green when they are 3 cm long. The tadpoles are 9 cm long before metamorphosis, after it they are only 1.5 - 2.5 cm long. The Lake Frog is able to reproduce at the age of 3 years, the life span is 6 - 7 years. The frog is under protection.