European Common Carp (Cyprinus carpio)

The carp is economically the most important freshwater fish in Europe. The original wild species (from the Black Sea, Sea of Azov, Caspian Sea and Aral Sea) has a laterally compressed body, moderately elongated and covered with large cycloid scales. The snout is blunt; the mouth is large with two pairs of short barbells. The color is dark on back and golden on the sides. The belly, pectorals and pelvic are light yellow, the ventral fin is orange and the caudal fin is grey with orange shade. Coloration changes depend on habitat.
The carp is a strong fish up to one meter long or even more and can weigh 20 kg (sometimes over 30 kg). It grows very fast in the first year but later can weigh less than ordinary carps. This type of fish reaches sexually maturity at the age of 3 or 4 – males are mature one year earlier. They spawn in May and June in shallow waters with a lot of vegetation at the temperature of 15°C. Their spawning is very loud and they often jump high out of the water. The eggs are attached to the vegetation and the incubation period last for five days. Then the young ones hatch at the temperature of 20°C (approximately three). They are 5mm long and cannot stay attached to the vegetation. When old enough, they feed independently on small organisms and later on larger zooplanktons. By the time they are 2 cm long, they are eating animals from the bottom of the water. Feeding depends on the water temperature. Carps stop eating in autumn, move to deeper parts of the water and become inactive. The European Common Carp lives in deep but still waters; in rivers and stagnant waters; in armbands and basins. Their diet consists of large aquatic insect larvae, mollusks, scales, worms etc. Plants are also very important for their diet. The carp usually goes hunting in the evening or at night.

 Catfish (Silurus glanis)

The Catfish is one of the largest fish of European waters. It has a long body without scales; a large head and an enormous mouth surrounded with 3 pairs of pulpy barbells – two on the upper part of the mouth and 4 chin barbels. The back fin is much shorter than the anal fin. The eyes are generally small and the nostrils look like short tubes. The colors depend on the habitat; the back is usually black, sometimes green, blue or brown; the sides are cream-colored while the belly has dark spots. This type of catfish can grow up to 2m long and can weigh over 100 kg. It lives in large and deep rivers and especially likes deep damns or embankments. If there is enough food, the catfish will grow very fast and by the time its 9 years old, will weigh 12-16 kg. It spawns in May and June at the temperature of 18°C in waters with a lot of vegetation. The female lays her eggs in a very messy nest; the male impregnates and guards them until they hatch. At first, the young ones feed on crabs and worms etc. Adult catfish feed on other fish (smaller species) but also prowl on frogs, small mammals or aquatic birds. The catfish has a great economic significance around the Black Sea. In the last few years the catfish has been breaded in carp fishponds as a secondary predator.

 Zander (Stizostedion lucioperca)

The Zander can always be differed from the perch because of the large gap between the back fins and the elongated body that is never strictly bended as the perch’s. The Zander is a strong fish, up to 1m long weighing even 10 kg. It has a gray-brown or gray-green back; and light silver-green colors on the side of the body. During the spawning season, the male has a blue belly while the female has a white one. This type of fish usually lives in deep but still waters. It likes to hide during the daytime and hunt during the night or early in the morning. The Zander is extremely sensible when there is lack of oxygen in the water or if the water is polluted. It spawns in April and May in shallow waters at the temperature of 6°C. The male makes a rough nest at the bottom of the water so that the female can attach her eggs to the aquatic plants or roots. The male guards the nest, cools the impregnated eggs with his fins so that they receive enough oxygen and protects them from the sludge and other agents. The young zanders like to stay in shallow waters and first feed on planktons and small insects. When they are 3-4 cm, they feed on cyprinid fish eggs. The adult zanders feed exclusively on other fish. They never prowl on large fish, like the pike does, but they can stay in fishponds together with carps.