Coastal Aquaculture and Mariculture (2+1)

Unit 5 - Finfish culture systems

5.4.2. Culture techniques

• Majority of the grouper production comes from open sea cage culture. They are also grown in coastal ponds and recirculatory systems.
• 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 are fed @ 10% biomass with mysids and small shrimp after a couple of days of acclimatization.
• When they have reached lengths of 12-15 cm they are transferred to nursery cages of 5x5x3m, each holding about 1100 fish. Cages are made of polyethylene net of mesh size 2.5cm.
• They are fed trash fish which is minced or chopped to size suitable to the size of growing fish at the rate of 8% of the biomass.
• After about 2-3 months they are transferred to production cages
• 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.
• E. tauvina reaches marketable size of 800g within about 6 months and two crops can be raised per year. Survival ranges from 60-90%. A production of 150 to 250Kg per cage is possible.

Pond culture:

• Groupers can be grown in earthen ponds and concrete tanks.
• Pond are prepared by drying liming and fertilization.
• The ponds are stocked with 5000 to 10,000 tilapia 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.
• The fish are fed chopped trash fish at 5% of grouper biomass.
• Feed trays are used for monitoring of feed intake. Water depth is maintained at 1-1.3m, temperature at 24-31^oC and dissolved oxygen at 5-9ppm.
• Fish are selectively harvested at a size of 400-600g using drag nets.
• Under sized fish are returned to the ponds to grow to marketable size. Duration of culture is 6-8 months. A production of 1.5 to 2 Kg/m³ is obtained by this method. Survival in pond culture of groupers varies from 70-90 percent.