54 MARCH 2015 • WORLD AQUACULTURE • WWW.WAS.ORG complete darkness by covering the tanks with green mesh sheets. On day 3 ph, the cover sheets were removed. In addition to the natural photoperiod, overhead fluorescent lighting was provided for 16 hours. Algae (Tetraselmis and Chlorella spp.) were added daily until day 25 ph at 10 percent of each LRT water volume to maintain a density of 50,000-100,000 cells/mL. From day 2 to day 8 ph, copepod nauplii, collected from shrimp ponds with 150-μm filter mesh were provided to silver sillago larvae at ≤1 individual/ ml. From day 2 to day 25 ph, rotifers Brachionus rotundiformis (66-150 μm) were added twice daily to maintain a density of 1015 individuals/ml in the LRTs. Rotifers were enriched prior to feeding for 6-8 h with super HUFA ( >45 percent ω3 fatty acids, >16 percent EPA, >30 percent DHA, >2.0 percent ARA). Because of the very small mouth opening, larvae were unable to consume rotifers and copepod nauplii at the onset of feeding and only algae cells were detected in the stomachs of larval silver sillago. During rotifer feeding, water exchange was done only at night at 30-50 percent of LRT volume. From day 18 to day 40 ph, enriched Artemia nauplii with super HUFA were added to LRTs at 0.50-0.75 nauplii/mL. The addition of artificial feed (Love Larva) started on day 20 ph with the small feed size of 198 μm (57.4 percent crude protein, 12.4 percent fat) until day 30 ph. From day 28 until day 35 ph, artificial feed of medium size (308-476 μm; 58.4 percent crude protein, 14.0 percent fat) was added and, from day 32 to day 40 ph, the larger size artificial feed (680-1058 μm; 56.2 percent crude protein, 3.5 percent fat) was provided. From day 35 to day 50 ph, trash fish paste was served to larvae. After weaning, fry were collected through the drain pipe, counted, weighed and measured to the nearest mm (Fig. 5). Overall larval survival was low (only 1.0 percent), mainly attributable to initial mortalities during the first week, probably due to lack of the proper size of prey for the silver sillago larvae to feed upon. In addition, one LRT was severely infected on day 38 ph with a parasitic protozoan Cryptocaryon irritans, resulting in a very low survival in that tank. The average body weight recorded was 180 ± 190 mg and the average body length was 2.60 ± 0.35 mm. Collected fry were transferred immediately to a 40-m3 growing tank and grown further for 32 weeks. During this period, fish were fed with 0.3-0.9 mm feed (52 percent crude protein) at 5 percent body weight per day and fresh whole sardines placed at the bottom of the tank. FIGURE 4. Stocking silver sillago broodfish in a 40-m3 tank. 3 h after spawning 15 h after spawning hatching - 26 h after spawning FIGURE 5. Collection of silver sillago fry. FIGURE 6. Growth performance of silver sillago over 32 weeks.
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