The test method described in this Test Guideline, is intended to define the lethal and sub-lethal effects of chemicals on the early life stages of the species tested.

The early-life stages of fish are exposed to five concentrations of the test substance dissolved in water, preferably under flow-through conditions, or where appropriate, semi-static conditions. The test starts with placing fertilised eggs (at least 80 per concentration level) in the test chambers (four at the minimum) and continues at least until all the control fishes are free-feeding. Lethal and sub-lethal effects are assessed and compared with control values to either determine the lowest observed effect concentration and the no observed effect concentration, or the effect concentration leading to x% change on organisms for the effect observed. The study report should include measurement of the concentrations of the test substance in water at regular intervals (five at least), the dissolved oxygen, the temperature, pH, total hardness and salinity, fish weight and length, observations of abnormal appearance, abnormal behaviour, hatching and survival, as well as the no-observed effect level or the effect concentration leading to x% change in the organisms for the effect observed.