Larval Rearing of the Giant Trevally, Caranx ignobilis (Forsskål, 1775), Fed Live Food Combinations of Rotifers, Copepods and Artemia salina

Abstract

The giant trevally, Caranx ignobilis, is a high value fish which has been studied for spawning in captivity and domestication in the Philippines in view of its aquaculture potential. Initial larval rearing of the species encountered mortality issues, and this study attempts to address the problem to improve their survival. Hatchery-bred C. ignobilis larvae were reared for 40 days in nine units of 100 L conical fiberglass tanks at a stocking density of 500 larvae.tank-1 under three feed treatments with different combinations of rotifers (Brachionus plicatilis), brine shrimp (Artemia) and copepods (Pseudodiaptomus spp.): T1- Brachionus plicatilis + Artemia, T2- Brachionus plicatilis + Pseudodiaptomus spp., and T3-Brachionus plicatilis + Pseudodiaptomus spp. + Artemia fed at 0800 h and 1600 h. The results showed that the inclusion of copepods in the feeding regimen had positive effects on survival. Survival rate was significantly higher (P < 0.05) in T2 (23.47 ± 3.18 %) than T1 (11.67 ± 1.90 %) but was not statistically different from T3 (14.37 ± 3.88 %). Length increment was significantly different (P < 0.05) among treatments but with no statistical difference in specific growth rate (P > 0.05). The erratic swimming behaviour leading to mortality associated with insufficient levels of highly unsaturated fatty acids in Artemia was not observed in T2, thus, validating the assumption that the feeding with copepods will increase survival during larval rearing. The use of copepods for C. ignobilis larviculture is seen to play an important role in the success of the seed production protocol for this species. However, a sustainable supply of copepods through appropriate mass propagation techniques must be ensured to achieve higher production of C. ignobilis seeds in the hatcheries.