Perch are the most common fish in Finland: one can find them in almost all lakes and coastal areas. Perch live to a maximum age of 30 years and may grow up to 50 centimetres long, and reach a weight of about three kilograms. Their diet consists of worms, insect larvae and small fish. When the opportunity arises, perches can hunt even quite big fish – a perch has even been seen to devour an eelpout almost as large as itself. Perch spend their early mornings and evenings swimming in large schools hunting for food. In the middle of the day they may sleep, like the pikeperch. Fish do not have eye lids, and consequently they sleep with their eyes open. Staying put means that a fish is sleeping. Perch spawn in May, and at that point the bottom of the Baltic Sea tank may be covered with a white veil. The veil consists of ribbons of perch spawn which the other fish, nor the Chinese mitten crabs in the tank do not eat, because perch spawn tastes bad. Hence, in June it is possible to see some small perches, but only for a while, because the other fish quickly eat them. You cannot see fry of the other fish in the tank, because the delicious spawn is eaten right after spawning. The quickest spawn eaters are eelpouts and eels.
