The distinguishing features of zanders are the 19-24 rays in the dorsal and 11-13 rays in the anal fins, the bare pre-opercula scaled only in part, and the strong fangs in the jaws. This largest of the family reaches up to 120 cm in length and 12 kilos in weight, although typically it is 60-70 cm and 2-4 kg. Its back is greenish gray with 8-12 brown black stripes on the flanks. The dorsal and caudal fins present dark spots and the rest of them are straw-colored. Zanders are found in the basins of the Baltic, Black, Azov, Caspian and AralSeas. Their areal grows owing to intensive human activities. It is a major game fish of the Pskov-PeipsiLake.
Two biological forms are distinguishable by life patterns – the resident and semi-anadromous. Resident zanders dwell in rivers and clean lakes. In lakes and reservoirs they settle in the pelagic zone, where they choose a layer based on the food distribution, oxygen content and water temperature. They prefer water of 14-18°С, and avoid water with unfavorable oxygen regime. Their roe is small and the fertility is high – from 200 000 to 1 000 000 eggs. Spawning starts in May with water temperatures of 13-14°С and lasts around 3-4 weeks. Males guard the roe, and clean it from mud by fanning water over it with their pectoral fins. Tempos of roe development depend on the temperature: at 9-11°С fry hatch in 10-11 days, and at 18-22°С – in 3-4. After the yolk is empty, fry feed on zooplankton. In their second month, they start preying on large invertebrates – mysids and cumaceans – as well as fish fry. If zander fry get enough of appropriate food, they grow fast and reach 10-15 cm by the fall. The pikeperch predates relatively small prey – the typical sizes of prey of a large zander are 8-10 cm. Diet favorites in the north are smelt and roaches, and in the temperate region – ruffe, perches, bleaks and roaches. Thus, it preys on fish of low value. It consumes 3.3 kilos of fish per kilo of its weight. This is less than a pike requires – let alone a perch. This is why it is a willingly bred species in many waters. Zanders mature 3-5 years of age. They are a very valuable game fish.
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