Clinical and physiologic effects of sodium chloride baths in goldfish (Carassius auratus)

Sodium chloride (salt; NaCl) has been used for freshwater fish to decrease stress and manage a variety of disease conditions. Recommendations for dose and duration vary greatly. The purpose of this study was to determine the potential adverse clinical and physiologic side effects of different concentrations of saltwater baths on goldfish. Eleven goldfish (Carassius auratus) were used in a cross-over study to assess the effects of three different salt concentrations (5, 10, and 20 g/L) on plasma biochemistries and clinical response. Baseline plasma chemistries were obtained and analyzed immediately prior to placing the goldfish into the saltwater bath and after the fish was removed. A 2-wk washout period was used in-between each treatment. Significant differences were found in fish in the sodium (10 g/L, P = 0.007; 20 g/L, P = 0.01), chloride (10 g/L, P = 0.006; 20 g/L, P = 0.001), and alanine aminotransferase (10 g/L, P = 0.002; 20 g/L, P = 0.004) after their exposure to 10 and 20 g/L saltwater. Glucose levels were found to differ significantly after exposure to all three NaCl concentrations (5 g/L, P = 0.0009; 10 g/L, P = 0.0001; 20 g/L, P = 0.0005). Clinically, 5 g/L and 10 g/L saltwater baths were well tolerated by the fish for the duration of the intended 12-hr treatments, with only one goldfish being removed during the 10 g/L bath at 7 hr for listlessness. The average time goldfish spent in the 20 g/L salt bath was 43 min, with six (54%) of the fish remaining in the 20 g/L salt bath for the intended 60-min treatment period. The remaining 5 (46%) goldfish were removed because they became listless or dyspneic. All of the fish recovered from the treatments without complication. The results of this study suggest that goldfish tolerate saltwater baths but that physiologic disturbances can occur at the higher doses.