Effect of different feeding levels on water quality, growth performance and survival of western white shrimp (Litopenaeus vannamei Boone, 1931) post larvae with application of biofloc technology

In this study، effect of different feeding levels on water quality، growth performance and survival of western white shrimp Litopenaeus vannamei post larvae were studied in biofloc rearing system. Shrimp postlarvae of PL10 with mean weight of 3±0. 7 mg and mean length of 4. 4± 0. 93 mm were fed for three weeks in fiberglass containers with 200 liters volume of water and density of 10 post larvae per liter in four tretments including one control with water exchange and three biofloc treatments at different feeding levels of 25، 20 and 15% of body weight. According to the results، in the values of water quality parameters including temperature، salinity، dissolved oxygen and pH، no significant differences were observed among the groups (P>0. 05). The highest increase in body weight (58. 42 mg)، growth rate (2. 78 mg per day)، specific growth rate (15. 09 %/day)، biomass (84020 mg) and survival rate (71. 9%) were obtained in biofloc treatment at 25% feeding level. The highest feed conversion ratio (2. 05) and the lowest feed efficiency (48. 62%) were obtained in water exchange treatment without floc، showing significant difference compared to the other treatments (P <0. 05). The results from this study reveals that by using biofloc rearing technology can decrease the amount of water exchange and feed utilization compared to body weight in culture of western white shrimp post larvae. Moreover، the presence of biofloc improves growth performance and production of L. vannamei post larvae in biofloc rearing system.