The acute toxicity of the water accommodated fraction (WAF) of XC 2732 and water to the rainbow trout, was investigated during a range-finding study conducted at T.R. Wilbury Laboratories, Inc. The test, which was designed to determine the approximate toxicity of the test substance, was performed from November 8 to 9, 1999. The test was performed at 12 plus or minus 1 degree C under static conditions with a control and the WAF of five nominal concentrations of test substance (0.05, 0.10, 0.50, 1.0, and 5.0 mg/L). Each concentration was replicated once, with live fish per replicate. The dilution water was carbon filtered deionized water collected at Marblehead, Massachusetts and adjusted to a hardness of 40 mg/L as CaCO3. Water quality was within acceptable limits throughout the test and no insoluble material was noted during the test. Juvenile rainbow trout that were obtained from a commercial supplier and maintained at test conditions for more than 14 days were used to initiate the test. Control survival at the end of the 24-hour range-finding toxicity test was 100% and no control sub lethal effects were observed.