Trial on nursing striped catfish (Pangasianodon hypophthalmus) from fry to fingerlings in oligohaline water using recirculating aquaculture system

Abstract

The study aimed to determine the adaptation of striped catfish (Pangasianodon hypophthalmus) larvae todifferent salinities and stocking densities. Two experiments were carried out in a Recirculating Aquaculture System (RAS) with 150-L fiberglass rearing tanks.One-day-old larvaewere stocked and fed on rotifer on the first 3 days, followed by Artemia nauplii up to day 7th, then they were weanedto commercial powder diet(40% protein) and commercial pellet (35% protein, diameter of 0.1mm) from day 21st. In the first experiment, larvae were stocked at the density of 5 fish.L-1 in salinities of 0, 3 and 6 ‰. Result after 30 days of rearing revealed that survival rate of striped catfish larvae was not affected since salinities raise up to 6 ‰. Growth rates of larvae reared in 3‰ and 6‰ (SGRs of 18.2±0.45 and 17.9±1.13%.day-1, respectively) was significantly higher than those of larvae reared in freshwater (SGR of 16.6±0.51%.day-1).Length increases of striped catfish larvae nursed in 3‰ and 6 ‰ (daily length increase, DLI of1.57±0.08 and 1.52±0.22 mm.day-1, respectively) was significantly higher than those of larvae nursed in 0‰ (DLI of 1.26±0.06mm.day- 1). Water quality: pH was maintained 6.4-8, dissolved oxygen (DO)ranged 5.8-6.4 mg.L-1, and the temperature was kept 28-32oC during culture period. TAN, Nitrites (NO2-), Nitrates (NO3-) and total bacteriain all treatments were in suitable range for the growth of striped catfish larvae. In the second experiment, larvae was reared in water salinity of 6‰, at 3 different stocking densities of 5, 10 and 15 fish.L-1. After 30 days of rearing, result showed that survival rate of striped catfish larvae at stocking density of 5 fish.L-1was better than the other two. Growth rates and length increaese of larvae nursed in different stocking density was not significantly different (p>0.05). Water quality: pH was maintained 6.8- 8.2, DO ranged 6.4-7 mg.L-1, and the temperature was kept 27.6-31.8oC during culture period. TAN,NO2-, NO3- andtotal bacteria in all treatments were in suitable range forthe growth ofstriped catfish larvae.