The Effect of Microbial Biofloc on Water Quality, Survival and Growth of the Green Tiger Shrimp (Penaeus Semisulcatus) Fed with Different crude Protein Levels I: Sustainable Solution to the Dependency on Fish Oil, Fishmeal and Environmental Problems

Onfarm trial were conducted to evaluate the effects of feeding on pellets with different protein levels in the presence and absence of the bioflocs on water quality, survival and growth of the green tiger shrimp (Penaeus semisulcatus) in intensive types of shrimp culture systems. Five different feeds were formulated. Four biofloc treatments (BFT) and one control were managed in 10 greenhouses earthen ponds of 300 m each: BFT fed feeds of 31.15% crude protein (CP) (BFA31.15%), 21.60% CP (BFB21.60%), 18.45% CP (BFC18.45%) and 16.25% CP (BFD16.25%) and a control without biofloc but fed a 42.95% CP feed. The bioflocs were developed in the BFT treatments using wheat flour as a carbon source. Thirty juvenile Penaeus semisulcatus with an average body weight of 1.55 ± 0.2 g were stocked per m and each dietary treatment and the control was tested in two replicates over a 120 days feeding trial. Biofloc diets enhanced shrimp growth. There was a significant differences (P<0.05) between control and treatment groups in terms of final average body weight (ABW) at harvest (15.1 ± 1.6; 19.8 ± 0.1; 19.2 ± 0.3; 20.1 ± 0.3 and 19.0 ± 1.1 for control; BFA31.15%; BFB21.60%; BFC18.45% and BFD16.25%, respectively) confirming the utilization of biofloc by shrimp as a food source. Concerning final shrimp yield per dietary treatment, there was a significant differences (P<0.05) between control and treatment groups at harvest (114.1 ± 5.3; 151.5 ± 7.9; 152.6 ± 7.4; 155.5 ± 6.9 and 153.6 ± 8.4 kg pond for control; BFA31.15%; BFB21.60%; BFC18.45% and BFD16.25%, respectively). The FCR differs significantly between BFT treatment and control (P<0.05). Growth (weight gain week) for control, BFA31.15%, BFB21.60%, BFC18.45% and BFD16.25% were respectively 0.85 ± 0.4; 0.98 ± 0.1; 1.00 ± 0.2; 1.11± 0.2; and 1.00 ± 0.2. The shrimp survival % was not affected (P>0.05) by the treatments and it ranged between 85.7% and 88.4%. The addition of carbohydrate to the water column (P<0.05) reduced the nitrate, nitrite-N levels and TAN in the experimental greenhouses. There was a significant differences (P<0.05) in the nitrate, nitrite-N levels and TAN concentrations between treatments and the control greenhouses. Simple economic calculation revealed that the lowest CP% BFT