Death
(5) Death means the lack of opercular movement by a test fish. (6) Flow-through means a continuous or an intermittent passage of test solution or dilution water through a test chamber, or a holding or acclimation tank with no recycling. (7) Incipient LC50 means that test substance concentration, calculated from experimentally-derived mortality data, that is lethal to 50 percent of a test population when exposure to the test substance is continued until the mean increase in mortality does not exceed 10 percent in any concentration over a 24-hour period. (8) LC50 means that test substance concentration, calculated from experimentally-derived mortality data, that is lethal to 50 percent of a test population during continuous exposure over a specified period of time. (9) Loading means the ratio of fish biomass (grams, wet weight) to the volume (liters) of test solution in a test chamber or passing through it in a 24-hour period. (10) Static means the test solution is not renewed during the period of the test. (11) Test solution means the test substance and the dilution water in which the test substance is dissolved or suspended.