In a previous article, published in the December 1960 issue of the Journal, the problems of treating water containing a fish poison were discussed, and data was presented on the ability of various water treatment processes to remove the toxic agents deliberately added to a water during fish management operations. This article reports the results of experiments on assessing the odor potential of various fish poison formulations and the ability of water treatment processes to remove these odors. It was shown that odor in a raw water supply occurring after contamination with the fish poisons tested may be removed effectively by activated carbon. No other common water treatment process will successfully reduce the odor of 2.0 mg/l of fish poison formulation to acceptable levels. The doses of carbon required for the formulations tested in this study were 36‐85 mg/l. Such carbon doses are unusually large and would be a serious economic burden in the routine treatment of water. But because fish poison formulations would be applied infrequently and because the odor of most of the formulations persists for only a short time, during which interval decreasing dosages of carbon are required, the increased cost of water treatment may not be very large. Use of formulations containing toxaphene would require sustained treatment with carbon because of the high stability of toxaphene. Because of the unusual odor problem and unknown composition of the solvents presently used in fish poison formulations, it is recommended that a more suitable solvent be developed for use in formulations intended for water supply application.