The preferred freshwater species are rainbow trout (Oncorhynchus mykiss) and carp (Cyprinus carpio).

The objective of this study is to determine the steady-state bioconcentration factor (BCFss). Fish are exposed under flow-through conditions to water of known quality to which the test substance has been added at known concentrations for a period normally not exceeding 28 days (uptake phase). After the uptake phase the remaining fish are transferred to clean tanks under flow-through conditions for a further period of time normally not exceeding 14 days (depuaration phase). Samples of fish and water are analysed for the test material at predetermined time points in both test phases.