The Golden Trevally Gnathanodon speciosus is a popular sport, food, and ornamental fish native to the tropical Indo‐Pacific region, yet there is little information regarding aquaculture technologies. A group of Golden Trevally broodfish was acquired from a local public aquarium in an effort to attempt captive spawning and larval culture. Broodfish were held in 4,500‐L recirculating aquaculture systems and conditioned on a mixed diet of squid, capelin, and krill. Once water temperatures were averaging 26°C, Ovaplant was administered to mature broodfish (six males, two females) in one of the systems. Broodfish spawned on three separate occasions after this hormone administration, releasing probably 35,000 eggs/female during each spawn. Fertile eggs from two of these spawns were used for larval culture attempts. Larvae were stocked into five 104‐L tanks at densities up to 173 larvae/L. Throughout larval culture trials, larvae were fed a combination of copepod nauplii, enriched rotifers, Artemia nauplii, and a dry diet, and the tank water was inoculated with live Tahitian strain Isochrysis galbana up to 26 d posthatch (dph). Larvae achieved complete metamorphosis around 30 dph. By 45 dph, nearly 4.3% of the larvae initially stocked survived and reached about 3.7 cm in length. These successful spawning induction and larval culture trials are promising for future development of a commercial‐level production industry for Golden Trevally.
Experiments were conducted on Guinean Fingerfish Monodactylus sebae to evaluate egg and larval stocking densities, stocking methods, water quality effects on egg hatching success, and the effects of different live food organisms on larval growth and survival. Egg hatching percentage was determined for four egg stocking densities (10, 20, 30, and 40 eggs/L). The lowest stocking density, 10 eggs/L, had a significantly higher mean hatching percentage (65.0 ± 18.54%) than the 30-and 40-eggs/L treatments but did not vary significantly from the 20-eggs/L treatment. Eggs were incubated in salinities of 0, 5, 10, 15, 20, 30, 40, 45, and 50 g/L to evaluate the effect on hatching success. The hatching success was over 70% for salinities of 0-30 g/L. The highest hatching success (98%) occurred in the 5-g/L treatment, and the 40-and 50-g/L treatments had significantly lower hatching success than all other treatments. Three live food organisms were fed to larvae to determine effects on growth and survival over a 9-d period. Diets were enriched rotifers Brachionus plicatilis, nauplii of the copepod Parvocalanus crassirostris, and nauplii of the copepod Pseudodiaptomus pelagicus fed at equal densities of 10 organisms/mL once daily. Larvae were stocked at 20 fish/L. At 9 d posthatch (dph), survival was not significantly different among treatments and larvae fed P. pelagicus had a significantly longer SL (mean ± SD = 4.28 ± 0.42 mm). Larvae were netted and exposed to air as a stressor at 6, 14, 22, 30, 38, and 46 dph for durations of 30, 60, 120, and 240 s. The 30-dph treatment had the lowest survival among all treatments regardless of experimental duration, followed by the 38-dph treatment. Results suggest that to avoid high handling mortality, Guinean Fingerfish should not be handled during metamorphosis (30-38 dph).
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