1. CULTURE OF GROUPERS

2. 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

3. 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 fish per day

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

5. 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 advanced fry or fingerlings
Fry and fingerlings - 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

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

7. 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 g 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 %

8. 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 cm, 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 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