Technology optimization of young carp and carp-crucian hybrid cultivation

To increase the resilience of young carp fish they should be maintained in a fish hatchery within 20-30 days. Fry ponds are used for this purpose. The objects of the research were the larvae of carp and carp-crucian hybrid. The objective of the experiment was to improve the living conditions of the larvae, and ensuring their natural food supply. The complex of agromeliorative works was done for this. Before pouring the ponds the plants were mowed and sanitization was done with chlorine or calcium hypochlorite by filling with water for 2-3 days and then sluicing it off. The refinement was done at the rate of 50 kg/ha. Organic and mineral fertilizers were added to improve the productivity of the pond. Organic fertilizers (rotted cow dung) was charged on dry areas of the ponds by plowing into the soil at the rate of 4 t/ha. Mineral fertilizers were putted in the water. Superphosphate (a mixture of salts of Ca(H2PO4)2 and CaSO4, containing 17% phosphoric acid (Р2O2) to achieve the maximum effect were used. The superphosphate was blended as 1 to 20 at the rate of 50 kg/ha. Ammonium nitrate (NH4NO3) was used as a nitrogen fertilizer by thoroughly dissolving in water at the rate of 30 kg/ha. Nitrogen and phosphate fertilizers contributed to the saturation of water with oxygen, increasing its vegetation characteristics and the active development of small zooplankton, which feed on the larvae. Oxygen concentration during the rearing period varied between 7-9 mg/l. The concentration of zooplankton averaged 500-1200 copies/l, and in certain periods reached 1200-1500 copies/l. As a result of the applied technique of carp larvae rearing without the use of artificial feed the volume of carp fry was 0.35-0.46 g. Hybrid fish grew more slowly than carp and the average weight of hybrid fry was 0.21-0.25. The larvae were experienced and active; their weight exceeds typical standards for fishery zone 1. The result of the experiment revealed that pasture rearing technology is quite effective if a complex impact on the ecosystem of fingerling ponds nutrients contained in fertilizers is employed.