CULTURE OF GROUPERS

Groupers -family - Epinephelidae. The major species for culture are Common name Scientific name Country Production (tonnes) Greasy grouper/brown spotted grouper Epinephelus tauvina Malasia Hong Kong 4400 822 Areolate grouper E. aerolatus 96 Red spotted grouper E. akaara - Humpback/High-fin/mouse grouper Cromilepties altivelis Singapore 1 Malabar grouper E. malabaricus Tiger/brown-marbeled grouper E. fuscoguttatus 64 Orange spotted grouper E. coioides Blue banded/yellow grouper E. awaora Red banded grouper E. fasciatus Giant grouper Epinephelis lanceolatus

Biology: Groupers - carnivorous fish associated with reefs Both in marine and brackish waters Feed on small fish and shrimp They are protogynus hermophrodites – mature as females and convert to males as they grow larger In Epinephelus tauvina sex reversal begins at the age of 6 years and the proportion of males increases thereafter Most fish become males after the age of 9 years For hatchery production of fish males can be got younger by hormonal sex reversal Functional males of E. tauvina could be obtained by feeding methyl testosterone for 14 days @1mg/kg fish per day

Seed supply Both wild and hatchery reared seed are used Survival rates – poor Majority of the seed is from the wild Fry measuring 3.5-5 cm are available during the breeding season Fishermen collect them with small seines and transport them for sale to fishermen

Culture techniques: Majority -open sea cage culture Wild fry or fingerlings are initially held in hapas for a month or more Hapas measuring 2x2x2 m are stocked at a rate of 400-600 advanced fry or fingerlings Fry and fingerlings - fed @ 10% biomass with mysids and small shrimp after a couple of days of acclimatization 12-15 cm -transferred to nursery cages (5x5x3m) each holding about 1100 fish Cages are made of polyethylene net of mesh size 2.5cm

Pond culture: Groupers can be grown in earthen ponds and concrete tanks Pond are prepared by drying liming and fertilization Stocking rate of tilapia- 5000 to 10,000 per hectare surface area Tilapia fingerlings serve as food for groupers Grouper fingerlings of size 7.5cm or more are stocked @ 5000 per ha one month after stocking tilapia

Feed - chopped trash fish at 5% of grouper biomass Water depth is maintained at 1-1.3m, temperature at 24-31oC and dissolved oxygen at 5-9ppm Selective harvesting at - 400-600g using drag nets Duration of culture is 6-8 months A production of 1.5 to 2 Kg/m3 is obtained by this method Survival rate-70-90 %

Feed - trash fish which is minced or chopped to size suitable to the size of growing fish at the rate of 8% of the biomass Transferred to production cages in 2-3 months Floating cages made of polyethylene netting of mesh size 2.5-5.0cm, supported by wooden framework are kept afloat with metal or plastic drums and anchored with concrete blocks Fish are stocked at the rate of 2-4/m³ They are fed with trash fish or pelleted feed @ 5% body biomass Marketable size of 800g in 6 months; two crops can be raised per year Survival 60-90%; A production of 150 to 250Kg per cage is possible