NURSERY REARING OF THE ASIAN SEA BASS, LATES-CALCARIFER, FRY IN ILLUMINATED FLOATING NET CAGES WITH DIFFERENT FEEDING REGIMES AND STOCKING DENSITIES

Successful rearing of hatchery-reared sea bass, Lares calcarifer, fry in illuminated floating cages was demonstrated in a 42-day experiment. Three feeding regimes, i.e. natural zooplankton (NZ)+ minced fish fle sh (MFF), NZ alone, or MFF alone and two stocking densities (600 and 1 200 individuals m(-2)) were tested in a 3 x 2 factorial experiment. Fi sh reared in unlit cages and fed MFF alone during daytime served as th e control. Results showed that no interaction existed between stocking density and feeding regime and that the two stocking densities used d id not influence fish growth in terms of mean final body size. In gene ral, sea bass reared in lit cages (NZ + MFF and NZ) grew and survived better than the control fish (MFF). However, fish reared under NZ + MF F feeding regime had the highest final mean total length (TL, 42.1 mm) and body weight (BW, 1311.8 mg) followed by fish reared under NZ feed ing regime (mean TL = 26 mm, BW = 415 mg). Fish in the unlit control c ages exhibited the poorest growth (final mean TL and BW: 26 mm and 277 .6 mg BW). Furthermore, specific growth rates (range: 5.7-8.5% day(-1) ) of fish in lit cages were significantly better than those of fish in the unlit control cages (mean: 3% day(-1)). Percentage survival (38%) of fish stocked at 600 m(-2) density and fed NZ was not significantly different from fish in the NZ + MFF feeding regime. However, increasi ng the density to 1200 ind. m(-2) tended to significantly decrease per centage survival (20%) of fish with NZ feeding. Fish reared in the unl it control cages had the poorest survival of 13-14%. The high percenta ge composition by number (CN, 88%) of copepods in the stomachs of sea bass fry fed on NZ alone and the equally high percentage feeding incid ence (94%) indicated that fish fed sufficiently on natural zooplankton . Supplemental feed using minced fish flesh contributed about 43-59% o f the fish diet in addition to natural zooplankton.