Studies on growth and survival in nursery rearing phase of grey mullet (Mugil cephalus) for mariculture

Abstract

The study was on the effect of stocking density on growth and survival of grey mullet, (Mugil cephalus) in floating net cages in closed bay, Bapatla. Triplicate groups of mullets with an average initial weight of 0.95 gm were randomly stocked in floating net cages (1m×1m×2m) at 20, 40, 60 and 80 fish/m3 designed as D20, D40, D60 and D80, respectively. Mullets in the cages were fed with 25% crude protein (CP) formulated diet at 10% of body weight twice daily. Sampling was done weekly. At the end of the experiment, growth in terms of body weight of fish was high in D20 than those in D40, D60 or D80, and in terms of weight gain, and specific growth rate of fish was high in D40 than those in D20, D60 and D80. The analysis of variance for growth performance showed among the treatments at 1% and 5% level of significance and better performance was observed at D20. There was a significant difference in the survival rates of mullets at different stocking densities. However, the survival was recorded at D20 (80%) and lowest at D80 (70%). At the end of the experiment survival rates was high in D20, then those in D40, D60 and D80. Total Feed Conversion Ratio was lower in D20 and D40, followed by D60 and D80. The cages stocked with 20 fish/m3 have highest growth performance and 80 fish/m3 showed highest biomass performance. Water quality parameters were at optimum level during study period. Results suggest that 20 fish/m3 could be recommended for producing better quality mullet fingerlings and 80 fish/m3 for highest number of seed production.