The crucian carp (Carrassius Gibelio) is the most famous and widespread freshwater fish in Romania. It belongs to the class Actinopterygii, order Cypriniformes, family Cyprinidae. The carp is native to North Asia, where it has spread throughout China as an ornamental fish, and later throughout the world. The usual dimensions of the crucian are 10-15 cm, and its weight can vary from 80-150 grams to 1.5-2 kg, exceptionally. In some cases they can be even over 30 cm
The color of his scales depends on the water in which he lives. In the muddy waters its scales turn black, in the waters rich in vegetation it turns green, and in the clear ones the crucian color is golden-brown. The shape of the head is similar to that of the carp, but it lacks a mustache, and the shape of the mouth is obtuse, with thin lips. The crucian carp can live in very oxygen-poor waters, within limits of pH, which few fish can withstand. It is a fish that resists and is taken out of the water for several hours, especially if it is wrapped in a wet cloth, because its scales do not dry out. It feeds on larvae, crustaceans, vegetation, mollusks, eggs, etc.
Reproduction is made in spring when the water reaches temperatures of 8-10 degrees. Spawning lasts until the end of summer. In this species all specimens over 2-3 years are females, because males, after this period suffer from the phenomenon called gynogenesis, ie their transformation into females.