The study is on using Supa-stock ® to stimulate growth of live food of phytoplankton and zooplankton rearing ponds and increase feed catching ability and growth of pangasius catfish fry. The experiment was conducted with 3 treatments including control (no Supastock ® ), 2 days before stocking, and 4 days before stocking. Three replications were set up for each treatment. Application of Supa-stock ® was implemented every day to day 10 after stocking. The area of experimental ponds was 2,500 m 2

more »

... water level of 1.3 m. Stocking density was 10 6 fries/1000 m 2 . Quantitative and qualitative samples of zooplankton were taken every day until day 10 to detemine zooplankton species composition and densities in the ponds. At the same time, fry samples were also collected to determine their feed composition and selection in the gut. The results showed that 65 zooplankton species were found belonging to four groups including Rotifera (27 species), Copepoda (20 species), Cladocera (13 species), and Protozoa (5 species). The zooplankton densities were in a range of 118,148 -5,777,037 ind./m 3 in which Rotifera was the most abundant group with high densities ranging from 50, 926 -3,788,889 ind./m 3 . Lowest density (0 to 32,593 ind./m 3 ) was recorded for Protozoa. Feed selection of catfish in the treatment with Supa-stock ® supplement 2 days before stocking was significantly (P <0.05) higher than that in other treatments. The study demonstrated that application of Supa-stock ® 2 days before stocking is the best in comparison with two other treatments.