2The Asian sea bass Lates calcarifer - important coastal, estuarine and freshwater fish in the tropical and subtropical Indo-Pacific regionIt is widely distributed from the Gulf of Arabia to Northern Australia.Highly Euryhaline with a complex life historyProtandrous hermaphrodite and catadromus fishSpawning occurs in brackish waters of 28 to 36 ppt salinity, near river mouths
3Spawns from January to August, spawning is triggered by a rise in temperature. spawns usually around full moon and new moon days coinciding with spring tidesHighly predacious and cannibalistic, which is the main difficulty in culture of this fishStringent size grading is required in the culture environmentsThe fish is fast growing and commands good price in local and international markets, hence this is one of the species cultured in Australia, Hong Kong, Singapore, Malaysia and Thailand.
4Source of seedFry - produced in hatcheriesFish - matured in sea cages and bred through environmental manipulation of hormonal injectionsWild ripe spawners can also be collected and stripped followed by dry method of fertilizationEggs hatch in hours at a temperature of 29-31°C
5They are hatched in seawater of salinity 30 ppt Larvae start feeding from the 2nd day onwards when they are fed marine rotifer Brachionus plicatilisFrom day 8 post hatch they are fed with Artemia nauplii or cladocerans25-30 days post hatch they are fed with ground trash fish meat/sub-adult and adult ArtemiaGrading is essential to prevent cannibalism starting from 2nd weed post hatch.
6Grow-out cultureIn recent years- floating cagesProblems –cannibalism and feedingGrow-out - performed in two phasesFirst phase- fry are grown to a weight of about 20 g in special nursery type of ponds of upto 2000m²Stocking rate /m².Besides natural food produced by fertilization, the fry are fed with supplementary feed consisting of ground trash fish twice a dayExchange of 30% per dayReared for 30 – 40 daysfingerlings of similar size sorted out and stocked in separate grow out facilities for growing to market size.
7Grow-out period - for 3-4 months in Philippines, where g fish are acceptable and 8-2 months in other countries where marketable sized fish is 700g to 1.2 KgFloating and stationary cages of different sizes (usually 50m²) are usedStocking density in cages is fish /m³, after 3 months stock is thinned out to 10-20/m³Feed chopped trash fish or pelleted feed specially formulated for Asian sea bassThey are 10% of the biomass twice daily for two months after which it is reduced to 5% once a day.
8In poly culture fish are reared with forage fish such as tilapias in the ratio of 1:20 The ponds are first stocked with the forage fish which reproduce rapidly and produce fry and fingerlings as food for the sea bassWhen sufficient food is produced sea bass juveniles are stocked at a rate of 3000 to5000 per haIn monoculture system sea bass juveniles are stocked at 10,000 to per ha with artificial feedingIntensive culture of sea bass has proved to be economical and a production of about tonnes can be obtainedThe stocked fish in ponds grows to 500g in 6 months; 800 g in one year and to 3 Kg in one and half to two years