Optimization of Cyprinids Larvae Rearing Technology in Earth Ponds Filled by Brackish Water through the Application of Soya Milk in Uzbekistan

Abstract

At 5.06-27.06. 2020, post embryonal larvae (0.004 g) of common carp (Cyprinus carpio), grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix) and bighead carp (Hypophthalmichthys nobilis) were reared in monoculturein earthen ponds (1-3 ha each) filled with brackish water. Soybean milk was made from bean that had been soaked for 7 - 9 hours in water and grinded with some water; in common, about 10 kg of milk was produced from 1 kg of soybean; 15 kg/ha of soybean was applied during experiment. The water temperature was higher than 22°C, pH varied within 6.9-8.1, water salinity was 2.6 - 3.5 о/оо, dissolved oxygen varied within 3.5-5.9 mg/l during the day. To the June the 27th silver carp fry reached 1.0 - 2.1 (on average 1.49) g, bighead carp 1.1 - 2.0 (1.61) g, common carp – 1.0 – 2.5 (1.43), grass carp – 1.3 – 2.7 (1.81) g. Food conversion rate of soya milk was 3.72, 9.82, 1.58, 2.84, respectively. Fry survival rate was 41 - 45 %.