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Abstract
The blackspotted croaker (Protonibea diacanthus) is a marine fish species with high economic value and aquaculture potential in Vietnam. However, the effects of ecological factors, especially salinity, on growth, survival rate, and feed utilization efficiency of this species during the juvenile stage have not been elucidated. This study was conducted to evaluate the influence of salinity on the rearing performance of blackspotted croaker juveniles. A single-factor experiment was designed in a completely randomized manner with five tested salinity levels: 10‰, 15‰, 20‰, 25‰, and 30‰. Juvenile fish, with an initial size of 3.29 ± 0.03 cm and 0.62 ± 0.07 g/fish, were stocked in 100-liter composite tanks at a density of 1 fish/liter. Each treatment was performed with three replicates for 28 days. Growth, biomass, survival rate, and feed utilization efficiency of the fish were assessed and compared among treatments. The results showed that these parameters were highest at salinity levels of 25 - 30‰, while the lowest performance was observed in the 10‰ treatment (p < 0,05). Compared to the 10‰ salinity treatment, the specific growth rate (SGR), biomass (BM), survival rate (SR), and feed conversion ratio (FCR) of fish at 25 - 30‰ salinity treatments improved by 8.30 – 9.13%, 28.8 – 33.4%, 13.6 – 16.4%, and 14.5 – 16.0%, respectively. No significant differences of evaluated parameters were found between the 25‰ and 30‰ salinity treatments, indicating that this salinity range is suitable for rearing blackspotted croaker juveniles. Thus, this study provided valuable information on the impact of salinity on blackspotted croaker, contributing to improving rearing performance and developing a complete technology for seed production of this economically important fish species.
Keywords: Protonibea diacanthus, salinity, growth, survival rate, feed utilization efficiency.