Growth performance and feed utilization of grey mullet fingerlings fed with varying levels of protein during nursery rearing phase

Aim: This study evaluates the growth performance and feed utilization of wild grey mullet fingerlings fed with varying levels of crude protein during the nursery rearing phase. Methodology: Grey mullet (Mugil cephalus) fingerlings were collected from the wild and were acclimatized under laboratory conditions before the start of the experiment. The fingerlings (initial average body weight of 2.82 ± 0.1 g) were stocked at 200 individuals per hapa (dimension: 2 × 2 × 1 m) in a brackishwater pond (2500 m³) and the experiment was conducted for 90 days in a completely randomized design with three replicates per treatment. Four experimental diets with graded crude protein (CP) levels of 30% (CP30), 35% (CP35), 40% (CP40), and 45% (CP45) on a dry matter basis were formulated using locally available feed ingredients and the effect of different levels of protein on growth performance was assessed. Results: At the end of 90 days of feeding experiment, the fish group fed with CP35 diet showed the best FCR (p < 0.05) and recorded the highest growth performance among different treatment groups. Increasing the protein content beyond 35% in the diet revealed no beneficial effect on various growth performance parameters. Interpretation: This study recommends the formulated diet with 35% crude protein for improved growth and survival of grey mullet fingerlings for farming in the pond based hapa system. Key words: Fingerlings, Grey mullet, Growth, Hapa, Protein