Ravindra Kumar Reddy, D (MAJOR)Chandrashekara Rao, AMADHAVAN, NSANTOSH KUMAR, TADANGI2021-07-152021-07-152017-11https://krishikosh.egranth.ac.in/handle/1/5810170541THESESThe present studies were conducted at the closed bay near Suryalanka, Bapatla, Guntur district on “Studies on growth and survival in nursery rearing phase of Grey mullet (Mugil cephalus) for mariculture”. Total two (2) studies were conducted. The first 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 g 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% 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. There was no significant difference in the survival rates of mullets at different stocking densities. At the end of the experiment survival rates was almost similar in D20, than 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. Another experiment was conducted to study the optimum crude protein for grey mullet, Mugil cephalus seed in floating net cages. Mullet fry were obtained through natural seed collection. Rectangular floating net cages made of bamboo poles were provided inside with 1×1×2m hapas. Predatory net and bird net were provided. PVC drums filled with air were fixed to the net cage for floating. Mullets with mean body weight of 0.95 g were stocked at the rate of 40 fish/m3 in each hapa in the rectangular cages. Triplicates were maintained for each treatment. Fish fry were fed with 5 artificial dry diets containing 12.5% (Control – C (T1)), 15% (T2), 25% (T3), 35% (T4) and 45% (T5) crude protein. The diets were fed at the rate of 10% of the biomass for a period of 63 days (9 weeks). Water quality parameters like D.O, pH, salinity, NH3, NO-2, NO-3 and temperature were estimated at weekly intervals and were within the optimum range for culture of mullet. At the end of 63 days growth experiment, fishes fed on 25% (T3) crude protein feed exhibited highest growth and survival performance at 1% and 5% level of significance. The present study showed that Mullets seed reared in floating net cages in the closed bay performed best at 25% crude protein.EnglishThesis