Stocking Density Effects on Pacific White Shrimp Litopenaeus vannamei Hatchery Performance in Algal‐Bacterial Biofloc Systems

The effects of stocking density of Pacific white shrimp Litopenaeus vannamei from hatchery stages nauplius 5 (N5) through postlarval 5 (PL5) were evaluated in algal–bacterial biofloc systems. Triplicate stocking densities of 200 (D200), 300 (D300), and 400 (D400) shrimp larvae/L were used. No water exchange or additional carbon source was conducted during the 14-d experiment. Compared with other groups, the D400 stocking density had significantly higher concentrations of total ammonia nitrogen and nitrite-nitrogen (0.55 and 0.66 mg/L, respectively). Nitrate-nitrogen and total nitrogen continuously accumulated throughout the experiment, with no significant difference among the three groups. The chlorophyll-a concentration, alkalinity, and pH of all three groups showed a downward trend in the later stage of the experiment. Shrimp larvae at the lowest stocking density had a higher survival during the rearing. Total Vibrio spp. count in the D200 group was lower than that of the other two but was not significantly different. In conclusion, we found that a stocking density of 200 shrimp larvae/L resulted in better survival and water quality conditions in the rearing systems tested.