n this Short-term Toxicity Test on Fish Embryo and Sac-Fry Stages, the life stages from the newly fertilized egg to the end of the sac-fry stage are exposed.The embryo and sac-fry stages of fish are exposed to five concentrations of the test substance dissolved in water. A choice, depending on the nature of the test substance, is possible between a semi-static and a flow-through procedure. The test starts with placing at least 30 fertilised eggs divided equally between at least three replicate test chambers per concentration, and is terminated just before the yolk-sac of any larvae in any of the test chambers has been completely absorbed or before mortalities by starvation start in controls. Lethal and sub-lethal effects are assessed and compared with control values to determine the lowest observed effect concentration and hence the no observed effect concentration. Alternatively, they may be analysed using a regression model in order to estimate the concentration that would cause a given percentage effect. The study report should include: the daily counting of the offspring, the daily recording of the parent mortality, the weekly measurement of oxygen concentration, temperature, and pH values; and the determination of the concentrations of test substance. It should also include the observations of abnormal appearance, abnormal behaviour, hatching and survival...