Coastal Aquaculture and Mariculture (2+1)

Unit 5 - Finfish culture systems

5.2.3. Grow-out operations

• In traditional coastal farming mullets are raised with other fish and shrimps.
• When tidal stocking is adopted the quantity and composition of stock can seldom be determined. This practice leads to under-stocking and presence slow growing species.
• The aquaculturists now supplement stock with fry and fingerlings caught from the wild.
• Neither feeding nor fertilization is practised in traditional culture system.
• Regular exchange of water is performed. Natural food enters along with the tidal water on which mullets and other fish feed.
• They also feed on benthic algal mat growing in the ponds. Production in this system varies from 150 – 1500 kg/ha.
• The more intensive polyculture is done in Hong Kong, Taiwan, Israel and to a lesser extent in Egypt.
• In Hong Kong mullets are stocked @ 10,000 to 15,000 fingerlings of 7.5 cm long along with 1000 to 2000 Chinese carps per ha.
• The stock is thinned out 3500 per ha when the fish grow to 12 cm size.
• The fish are fed rice bran for the first two months and thereafter a mixture of rice bran and oil cake.
• Organic manures are added to increase the production of natural food in the ponds. Production varies between 2500 to 3500 kg/ha/year.
• In Taiwan stocking is done with fingerlings of 3000 mullets, 2000 milkfish, 3250 Chinese carps and 500 common carp.
• Ponds are fertilized with super-phosphate @ 60 kg/ha.
• Fish are fed a mixture of rice bran, soya bean cake and peanut meal.
• Striped mullet attains a weight of about 300g in one year and 1.2Kg in the second year. 3 year old fish reach a weight of 2 Kg under pond conditions.