Chronic effect of nitrite on the rearing of the white shrimp Litopenaeus vannamei in two salinities

The aim of this study was to determine the effects of nitrite on the growth and survival of the white shrimp L. vannamei in two different salinities. Nitrite concentrations tested in salinity 8 g/L were 0 (control), 2.5, 5.0, 10.0, and 20.0 mg NO₂^?-N/L, and in salinity 24 g/L were 0 (control), 5.0, 10.0, 20.0, and 40.0 mg NO₂^?-N/L. For these experiments, 30 experimental units with 30?L of useful volume were stocked with 20 juvenile L. vannamei (8.0 ± 0.50 g), corresponding to a stocking density of 100 shrimp/m², and cultivated for an experimental period of 30 days. A significant difference was found between the control and treatment groups with respect to growth and survival. The 2.5 mg NO₂^?-N/L treatment showed the best performance indexes in salinity 8 g/L, while the best growth performance indexes were found in the control and 5.0 mg NO₂^?-N/L treatments in salinity 24 g/L. Total mortality was observed in the 10 and 20 mg NO₂^?-N/L treatment groups from salinity 8 g/L and in the 40 mg NO₂^?-N/L treatment group in salinity 24 g/L. This study determined that concentrations of nitrite of up to 2.5 and 10 mg/L are acceptable for the rearing of L. vannamei in salinities of 8 and 24 g/L, respectively.