54 SEPTEMBER 2015 • WORLD AQUACULTURE • WWW.WAS.ORG perch is becoming important. According to the Federal Agency of Fisheries, 10,338 t of river perch were caught in the waters of the Russian Federation and 929 t in the Astrakhan region in 2010.1 Low-cost production of perch using natural resources on fish farms provides a good return. The meat of perch has good dietary properties, with a protein content of 18.5 g/100 g of edible portion (Carasciuc and Petrichenko 2006, Jankowska et al. 2007). Perch products are very popular in Europe, where perch is grown in polyculture with carp, catfish and pike in large pond systems. Pasture cultivation of perch previously was confined to the Czech Republic, Hungary, Poland and France, but it is now of interest in Bulgaria, Ireland and Switzerland. Growing perch in Belgium, France and Switzerland started with the use of recirculation systems (Ponomarev and Fedorovykh 2006). The cultivation of Eurasian perch Perca fluviatilis is a potential opportunity to expand commercial fish farming. The high number of its population and its economic importance and central position in the composition of fish communities of many natural water bodies has stimulated great interest among researchers in many countries (Ponomarev and Fedorovykh 2008). Until recently, river perch was considered a low-value species in Russia. This is related largely to low demand in the country for this fish and the infestation by Eustrongylides roundworms (60-70 percent of total catches). These nematode worms penetrate deep into the muscles of perch, spoiling meat quality and leading to the culling of fish, raw materials and products (Vuchkova 2000). However, with the decline in stocks of major commercial fish species such as sturgeon, salmon, some anadromous carp and pike-perch, Eurasian The Biological Basis of Rearing Eurasian River Perch Larvae and Fry Yu.V. Fedorovykh, S.V. Ponomarev and Yu.M. Bakaneva TABLE 1. Stages of Eurasian (river) perch post-embryogenesis (Konstantinov 1957) with additions Number Age, Length, Stage of development of stage days mm 1 1 3-4 hatching 2 2-4 4-6 intense pigmentation of the eyes, intestinal peristalsis, the appearance of pigmentation along the intestinal tube and the ventral part of the body in the middle of the tail, the fat droplet moves away from the head. 3 4-5 6-6.5 the beginning of resorption of yolk sac 4 5-7 7 the beginning of the formation of the caudal fin, swim bladder filled with air, the lower jaw becomes longer than the upper. 5 7-9 8-9 formation the rays of the caudal fin, ventral fins are appearing, the anal and second dorsal fins formed, the teeth are formed, the eyes are large, up to 34.5% of the head. 6 10-12 10-11 ventral fins become visible, the rays in the second dorsal and anal fins formed, in caudal fin they have been already well developed, the body is transparent, although the number of pigment cells was increased, especially on the brain, here comes the first dorsal fin. 7 12-15 12-15 rays in all fins formed, fin fold disappears 8 16-17 15-17 the formation of scales, the body is elongated, well developed paired and unpaired fins, the largest pigment cells are located above the brain, the intensity of breathing larvae increase 9 18-20 15-20 fry period, the stomach starts formation, pyloric appendages increases.
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