Nursery rearing of Amur carp (Cyprinus c arpio haematopterus) fry in floating cages in a tropical large reservoir of India: Influence of stocking density on growth performance and survival

The study was carried out for 90 days in floating net cages installed at Maithon Reservoir, Jharkhand, India, with the aim of assessing the growth performance and survival of Amur carp fry at varied stocking densities. The Amur carp seed (4.38±0.19 cm and 2.08±0.28 g) was raised in galvanised iron (GI) cages at three stocking densities (SD) of 100, 200 and 300 nos. m3, i.e., SD 100, SD 200 and SD 300 were considered as low, medium and high stocking densities. The stocked fish were fed with commercial floating pellets containing 32% crude protein and 4% crude fat, at a rate of 5-3% of their body weight, twice daily (at 10:00 and 16:00 hrs). The water quality parameters were checked from within the cage and  at distances of 50 and 100 m from the cages at on a monthly basis. The results of this study demonstrated that stocking density had a significant impact on the growth performance and survival rate of Amur carp. The growth attributes, comprising weight gain (WG), absolute growth rate (AGR), and specific growth rate (SGR), were considerably higher at a lower stocking density of SD 100 compared to a higher stocking density of SD 300. Lower-density (SD 100) exhibited greater feed efficiency and effective feed utilisation compared to SD 300. No significant difference was observed in condition factor (K) among the treatments. The findings of the current investigation indicated that the stocking densities of 100 and 200 numbers m-3 showed no significant variations in terms of feed utilisation, growth, or survival. The results of the present study showed that stocking densities ranging from 100 to 200 numbers m-3 may be optimal for the higher growth performance and survival of Amur carp in inland cages. The viability of rearing Amur carp in cages for nursery purposes was investigated for the first time, in this study. Keywords: Amur carp, Cage culture, Growth,  Species diversification, Stocking density