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 MalasiaHong Kong

4400822

Areolate grouper E. aerolatus Hong Kong 96

Red spotted grouper E. akaara Hong Kong -

Humpback/High-fin/mouse grouper

Cromilepties altivelis Singapore 1

Malabar grouper E. malabaricus - -

Tiger/brown-marbeled grouper

E. fuscoguttatus Singapore 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