Dynamic of stress response in Labeo Victoria (Labeo victorianus) during transfer from the grow-out to cages and ponds under differential caged stocking densities
Ngugi, Charles C.
Kuria, G. M.
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Varying stocking densities have been suggested to obtain optimal growth performance, yields and economic benefits in fish culture. Transferring fish directly from hatcheries to the cages or ponds may induce stress. We evaluated the stress response of Labeo Victoria (Labeo victorianus) in an integrated cage-cum-pond culture during transfer of fish from the hatchery to the cages and ponds at different stocked biomass. Cages were stocked at varying biomass of 10, 30, 60, 90, 120, 150 and 180 fish/m3 and suspended in a static pond of 1300 m2. The L. victorianus fingerlings of a mean weight 23.6 ± 1.8 g were stocked in the cages and the pond respectively. 20 fish were sampled during the transfer period from the ponds and cages for analysis of primary and secondary parameters of stress response. Primary stress response occurred when fish were directly transferred to cages and ponds at stocking density ≥ 60 fish/m3 and 90 fish/m3 respectively. Parameters of secondary stress response occurred in fish transferred to the cages at stocking density ≥ 120 fish/m3 and in ponds at biomass ≥ 150 fish/m3.