Use of hiding space to increase the stocking density and production of estuary grouper, Epinephelus salmoides reared in floating net cages

Abstract

The relative growth and production of estuary grouper (Epinephelus salmoides?) in response to seven combinations of hiding space and stocking density were studied. The experiments were conducted in floating net-cages. Used car tyres were suspended in the net-cages to provide hiding space for the fish. The seven combinations of hiding space and stocking density were as follows:- 3 Hiding Space (cm³/fish) : 0 116 181 222 251 272 289 Stocking Density (fish/m³):60 24 103 132 156 180 204 Provision of hiding space in the net-cages has been found to permit further increase of the optimal stocking density from the usual rate of 60 fish/m3 to 153 fish/m³. The net-production was found to increase from 8.5 kg/m3 to 19.5 kg/m³ after three months. Growth in terms of weight-gain per fish, survival rate and food conversion ratio at stocking ates below 156 fish/m with hiding space between 116 - 222 cm³/fish were comparable to those observed at the optimal stocking density without hiding space (60 fish/m³). The growth of fish stocked at 180 - 204 fish/m³ with hiding space of 272 - 289 cm³/fish respectively was found to be significantly depressed.