Use of Iodized Versus Non-iodized Sodium Chloride in Therapeutic Dips and Baths for Freshwater Fish

Abstract

Salt (NaCl) is a common therapeutant in fish culture. The use of salt containing iodine may be harmful to fish. The goal of this study was to determine if using iodized saltfor dips and baths increases morbidity/mortality of fish and establishes the LC₅₀ of iodine for three commercially important species: koi, Cyprinus carpi; guppy, Poecilia reticulata; and Jack Dempsey, Rocio octofasciata. Fish were exposedto a salt bath (4 g/L) or a salt dip (25 g/L) using either iodized or non-iodized salt and observed for clinical signs of iodine toxicity or death. For the LC₅₀ trials, one fish of each species was exposed to a range of iodine concentrations for a period of 24 h. There were no significant differences in mortality between fish treated with iodized vs. non-iodized salt. The use of iodized salt for baths and dips appears to be safe in the three species tested. LC₅₀ of iodine in these species appears to be greater than 1.4 mg/L.

Keywords:

• Iodine toxicity
• salt
• dips
• bath
• koi
• guppies
• cichlids