The survival of Flexibacter columnaris was studied in a variety of waters containing different concentrations of 4 cations. The survival of F. columnaris over a period of 7 days was found to be optimal at the concentrations of 0.03% NaCl, 0.01% KCl, 0.002% CaCl₂·2H₂O, and 0.004% MgCl₂·6H₂O, respectively. The best survival was obtained in the formulated water medium containing the combination of the four cations at their respective level of optimum concentration. The survival of F. columnaris in the formulated water was very high and almost similar to the survival in tap water; whereas, distilled water did not support the long-term survival of F. columnaris. The survival of F. columnaris in the media containing single salt at their optimal concentrations were similar to each other but notably lower than the survival in the formulated water and tap water.