Acute salinity tolerance of juvenile platy, Xiphophorus maculatus

Common salt (99.3% of sodium chloride) is used as a water additive to reduce management stress in ornamental fish. Therefore, specific information on fish tolerance to water salinity is needed for establishing safe limits for salt use. In this study, we aimed to evaluate juvenile platy, Xiphophorus maculatus, for stress response and tolerance to acute salinity exposure. The fish were exposed to 0, 5, 10, 15, 20 and 25 g common salt/L water, for 96 h. Each aquarium containing 15 fish was considered an experimental unit. Mortality was quantified throughout the all-experimental period, and blood glucose was measured at 24 and 96 h. Survival probability was high (>90%) in platy exposed to 0, 5 and 10 g common salt/L water. The median lethal concentration (LC50) was estimated at 16.54 g common salt/L water, by logistic regression analysis. Platy showed an increase in blood glucose at 24 h with increased salinity, but glucose levels decreased at 96 h of in fish exposed to 10 and 15 g/L. These findings suggest that short periods of exposure to common salt in water trigger stress responses in juvenile platy. Therefore, common salt should not be used in the handling and transport of platy, at the exposure times evaluated.

Automated summary

This study evaluated the stress response and tolerance of juvenile platy to water salinity, showing that platy exposed to 0, 5, and 10 g common salt/L water had high survival rates, with an estimated LC50 of 16.54 g common salt/L water, and blood glucose levels increased with salinity exposure.