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.. <br />• . r `- • <br />have been used to date for alI bioassay work: Roam 1 of the Small Animal <br />Laboratory (SAL) and Room 113 (R113) of the Forestry Building. A third <br />' area, Room 20 (R20) of the Forestry Building is presently being prepared <br />~. for holding fish. The fish in this room will be maintained at higher <br />temperatures. ~`' <br />Test vessels used in fists bioassays include batteries of 1.9 and 18.9 <br />liter clear glass jars and 700 liter circular fiberglass vats. <br />Methods <br />S <br />Static acute toxicity bioassays follow procedures, in. so far as <br />possible, proposed by the Committee on Ai~thods for Toxicity Tests with <br />Aquatic Organisms (1975). <br />Depending on the availability and, the size of postlarval and juvenile <br />stages, 10 or 20 fish were normally used for definitive bioassays. The <br />bioassays with subadults contained 10 fish per 700-liter vat. The maximum <br />bioassay load was mostly limited to O.S g of fish per liter of water. With <br />a minimum of 10 fish per assay and a 0.8 g/1 load limitation, the maximum <br />i <br />average weight of the subadults that could be simultaneously tested in one <br />' vat was about SO grams. As juveniles average less than 5 grams, the difference <br />~ in weight between juveniles and subadults is at least tenfold. This tenfold <br />difference should be sufficient to detect any marked effect that size might <br />have on the tolerance of fish to a chemical. <br />Range-finding tests were made to determine the approximate toxicant <br />i concentrations that should be used in definitive tests witty each chemical <br />using juvenile squawfish at 17 C. Generally groups of five fish were placed <br />f~s~ 96 hours in a control aquarium and in experimental aquaria that contained <br />three to five logarithmically spaced toxicant concentrations. <br />' Mi: <br />