The effect of different stocking densities of marine shrimp larvae Litopeneaus vannamei on growth performance and survival rate using biofloc technology

There is a need to develop diets for shrimp cultured in Egypt in different rearing systems that will provide sufficient protein for shrimp production while minimizing the amount of nitrogen being introduced into the culture medium. Biofloc technology (BFT) is a new application in keeping up good water quality and growth performance of shrimp cultured. The present experiment was conducted to investigate the effect of three different stocking densities of Litopeneaus vannamei and the carbon source (sugarcane bagasse) with biofloc and commercial diet (38% CP) with a control system. The impact of the aforementioned variables was recorded with respect to water quality, microbial communities, biofloc composition, growth performance, feed utilization, and survival rates of shrimp. Shrimp were stocked with different densities (12, 14 and16 larvae/l) in 18 tanks with a water volume of 150 L for 90-days; triplicate groups of shrimp for both biofloc treatment and control. Shrimp were fed thrice daily at a ratio of 14% of body weight (initial weight of mean 0.002g) and re-adjusted gradually to 5% at the end of the experiment. The water quality parameters {temperature, salinity, PH, total ammonia nitrogen (TAN), nitrite (NO₂), nitrate (NO₃), phosphate (PO₄), total suspended solids (TSS) and biofloc volume (BFV)} were suitable for culture of L. vannamei in biofloc and control treatments. TSS and BFV were significantly higher in biofloc treatments compared to control. Growth performance and survival rate were better in all biofloc treatments. The results suggest that 16 larvae/l BF treatment is the best stocking density according to the economic analysis. The addition of a carbon source into L. vannamei culture reduced the total ammonia-N compounds, increasing total heterotrophic microorganisms. Furthermore, the increase in total heterotrophic bacteria loaded an effect on the increase of the zooplankton community which, in return, improved the growth performance and survival rate of shrimp.