World Aquaculture 35 tle flow of 37 ppt seawater. Water temperature during egg incubation was 21.7 ± 0.8° C. Hatching rates attained after 30-36 hours for group A (55.3 percent) and group B (56.8 percent) were similar (Table 1). Larval Rearing Hatched larvae, averaging 1.9 ± 0.1 mm in total length, were stocked in indoor 4-m3 concrete rectangular larval rearing tanks (LRTs) at 40 larvae/L. Green algae, Nannochloropsis (1.8 million cells/mL), was added to LRTs from day 3 to day 22 after hatching at a daily rate of 400-600 L/tank. Beginning day 3 to day 20 after hatching, larvae were fed rotifers (66-146 µm). Rotifers were added to rearing tanks twice daily from cultures fed baker’s yeast, Saccharomyces cerevisae, plus Nannochloropsis, and enriched six hours before feeding to fish larvae with HUFA at 0.25-0.35 mL/ million rotifers. The density of rotifers in LRTs was always maintained at 15 individuals/mL. Beginning day 15 until day 25 after hatching, fish larvae were fed newly hatched and enriched Artemia nauplii at 0.5-1 nauplii/mL twice daily. The enrichment of Artemia followed the same protocol for rotifer enrichment. From day 11 to day 25 after hatching, smallsize (198 µm) artificial feed was served. From day 20 to day 35 after hatching a medium-size (<200 µm) feed was added, and from day 30 until weaning (day 45) larvae were fed a larger-size feed (200-300 µm). Water exchange in LRTs beginning day 1 after hatching until day 33 was carried out at night by flow-through of 37 ppt seawater. In the first two days after hatching, the daily water exchange rate was 60-80 percent and from day 3 to day 33 it was 80-100 percent. From day 34 up to weaning (day 45), seawater was continuously supplied to provide 200 percent water exchange per day. During the administration of artificial feed, water flow was stopped for 30 minutes. Rearing water temperature ranged between 22.5 and 24.0 °C and the dissolved oxygen was maintained at 5.2 ± 0.2 ppm. The photoperiod was maintained at 14 h light and 10 h darkness. On day 30 after hatching, mortality was observed in some LRTs and tests of the dead larvae revealed the presence of monogenean parasites. All tanks with fish infected with this parasite were successfully treated with copper sulfate pentahydrate at 0.05 mg/L for seven days. After 45 days, all surviving juveniles were harvested. The total number of juveniles collected (150,000) amounted to 5.5 percent survival. The average weight of 45-day juveniles was 46 ± 35 mg and the average fork length was 1.4 ± 0.4 cm. All harvested juveniles were transferred to 40-m3 indoor concrete circular tanks for nursing at a stocking density of 1 fish/L. In the first 25 days the fish were cultured at 37 ppt Fig. 2. Female Rhabdosargus sarba. Table 1. Spawning performance of Rhabdosargus sarba and hatching rates. Group Treatment Total eggs No. eggs/kg ♀ fertilized eggs Hatching rate (x 1000) (x106) (x1000) (%) (%) A HCG + LH-RHa 3,710 594 71 55 B HCG 3,410 574 66 57 Fig. 3. Male Rhabdosargus sarba with running milt. Fig. 4. 406-µm cannulated oocytes.
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