ISO 20665:2008 specifies a method for the determination of the chronic toxicity to Ceriodaphnia dubia (Cladocera, Crustacea), based on reproduction inhibition after (7 ± 1) d.

The method is applicable to: a) chemical substances which are soluble or which can be maintained as stable suspensions or dispersions under the conditions of the test; b) industrial or sewage effluents, if appropriate after decantation, filtration or centrifugation; c) fresh waters; d) aqueous extracts (leachates, eluates, and elutriates).

ISO 20665:2008 is not applicable to the testing of aquatic samples from the estuarine or marine environment.