Analysis of Growth, Nutrition and Economic Profitability of Gibel Carp (Carassius auratus gibelio ♀ × C. carpio ♂) Cultured in Zero-water Exchange System

Gibel carp (Carassius auratus gibelio female x C. carpio male), a representative mudflat aquaculture species, was used to evaluate the effects of biofloc technology (BFT) on growth, nutrition and economic profitability in mudflat fish aquaculture. A 60-d experiment was conducted in zero-water exchange BFT system. The results demonstrated that weight gain (WG), specific growth (SG) and survival in BFT group were 133.94%, 1.20% day(-1) and 90.0%, respectively. In control group with a 1/4-1/3 daily water exchange, WG, SG and survival were significantly lower than those in BFT group. There were no statistical differences in crude protein (CP), crude lipid (CL) and ash contents of gibel carp muscle between BFT and control group at the end of experiment (P >0.05). The essential amino acids, non-essential amino acids and total amino acids contents of gibel carp muscle in BFT group were higher than those in control group. Bioflocs were composed with 29.8% CP, 3.2% CL and 19.1% ash at day 60. CP content was appropriate, and LP was lower for gibel carp. Economic profitability analysis included analysis on gross revenue, break-even production, net present value, payback time, degree of operating leverage, and environmental costs under experimental conditions was conducted. Analysis results revealed that BFT system was more effective than the control system with water exchange in gibel carp culture, suggesting that BFT system could be successfully used in gibel carp aquaculture.