ABSTRACT
The use of reference toxicant in aquatic toxicity testing is a part of efforts to obtain good quality data and it can be justified scientifically. It is used to determine the health and sensitivity of the test on organisms; to compare relative toxicities of substances by using control as an internal standard; to perform interlaboratory calibrations; and to evaluate the reproductive ability on tested data with time. Numbers of substances, such as some metals and salts, can be used as reference toxicants, but basically we must consider certain criterias in using a chemical as a reference toxicant. An ideal reference toxicant is that has a toxic at low concentrations, rapidly lethal, non selective, and detectable by known analytical techniques. The use of each reference toxicant in toxicity tests should be repeated using the same test organism to produce a data set of sensitivity. Endpoint values are then plotted on a control chart with tolerance range 2 SD. The value outside the tolerance range requires the evaluation of all test procedures and conditions of the test organisms.