Effects of light intensity on husbandry parameters, digestive enzymes and whole-body composition of juvenileEpinephelus coioidesreared in artificial sea water

Abstract

To provide a specific lighting system to aquaculture, a completely randomized design with five light treatments with three replicates was used to investigate effects of light intensity on juvenile Epinephelus coioides reared in artificial sea water. The weight gain rate (WG, %), specific growth rate (SGR % day−1), protein efficiency ratio (PER) and survival rate (S, %) were significantly higher at the 320–1150-lx treatments (P ≤ 0.05) compared with the other treatments, but the highest food conversion ratio (FCR) was at the 0-lx treatment and the lowest at 600–1150 lx. Total protease, amylase and lipase activities in liver, stomach and intestine were significantly higher at 320–1150-lx conditions and significantly lower at 0 lx (P ≤ 0.05) than in the other treatments. The highest contents of crude protein and crude lipid were observed at 600–1150 lx and 320–550 lx respectively. However, both moisture and ash were highest at 0 lx and lowest at 600–1150 lx. The results indicated that light intensity could significantly affect husbandry parameters, digestive enzymes and whole-body composition of juvenile E. coioides, with optimal light intensity being at 600–1150 lx.