Effect of copepod Apocyclops dengizicus addition on growth, survival, and proximate composition of Macrobrachium rosenbergii postlarvae cultured in brackish-water biofloc system

Abstract

Objective: The effects of periodically adding the cyclopoid copepod Apocyclops dengizicus (every 4 days at a rate of 4 individuals/mL) with biofloc technology (BFT-C) was compared with conventional biofloc technology (BFT; without copepod) or a clear-water control for Macrobrachium rosenbergii postlarvae nursery culture. Methods: Survival, growth, proximate composition, and economics of SMacrobrachium rosenbergii postlarvae was calculated. Water quality and biofloc proximate composition were also measured among treatments. For the BFT, maize starch was applied to achieve a C:N ratio of 20:1. Triplicate 125-L polyethylene tanks containing 500 postlarvae each (9.40 ± 1.88 mg) were evaluated. Result: Specific growth rate was significantly greater in the BFT-C group (8.40 ± 0.24% per day) than BFT (7.23 ± 0.21% per day) and control (7.12 ± 0.42% per day) groups. Postlarvae survival was significantly increased with the BFT-C (94.46%) treatment compared with the BFT (87.33%) and control (82.60%). A significantly lower food conversion ratio (1.08) was obtained in BFT-C than both the BFT (1.73) and control (1.90), possibly due to significantly higher biofloc crude protein and lipid contents in the BFT-C than BFT. Postlarvae whole-body protein and lipid contents were significantly elevated in BFT-C compared to the BFT and control treatments. Economics of gross return, net return, and cost-benefit ratio were significantly better at BFT-C than in either the BFT or control groups. Conclusion: This study indicates that copepod additions with BFT enhanced prawn postlarvae survival, growth, and whole body protein and lipid, as well as economics, which could augment productivity and sustainability in this industry.