Optimum stocking density and feeding level for laboratory-reared early-stage silver therapon (Leiopotherapon plumbeus) larvae

摘要

Growth, survival and feeding of early-stage silver therapon Leiopotherapon plumbeus larvae reared at different stocking densities and feeding levels were examined. Larvae (8 days post hatch (dph); 0.38-0.50 mg body weight (BW); 5.33-6.90 mm in total length (TL)) were stocked at densities of 5, 15, 25 and 35 larvae/L and co-fed with live food (Brachionus rotundiformis and Artemia nauplii) and formulated microdiet or fed Artemia alone for 28 days. Another batch of 8 dph silver therapon larvae (0.65 mg BW; 9.47 mm TL) were stocked at 15 larvae/L and were fed 1, 2 or 5 Artemia nauplii/mL for 28 days. Survival at lower densities (5 and 15 larvae/L) was significantly improved than in high-density reared larvae. Furthermore, larvae fed Artemia alone showed higher survival (20.4%-81.4%) than those offered live food and formulated microdiet combined (3.5%-32.9%) in each stocking density, indicating the suitability of Artemia for early-stage silver therapon larvae. Growth parameters were significantly affected by stocking density in larvae fed Artemia alone but not in the live food and formulated microdiet co-fed group. No significant differences in growth and survival were observed in silver therapon larvae reared on three feeding levels. However, higher feed intake at 5 nauplii/mL resulted in significantly higher body lipid contents than those fed 1 or 2 nauplii/mL. The results suggest that larvae held at stocking densities of 5 and 15 larvae/L and fed 5 Artemia nauplii/mL promote maximum growth, survival and higher feed intake of early-stage silver therapon larvae under laboratory conditions.