Aquatic nanotoxicology is the science of studying the effects of nanomaterials on aquatic organisms with a history of less than a quarter of a century. As an inhabitant of aquatic ecosystems, fish may be exposed to a wide range of contaminants, including nanomaterials. Although there are benefits to studying the effects of pollutants using fish, it is not always necessary and the scientific community is always looking to reduce the use of vertebrates such as fish for hazard identification, risk assessment and safety assessment of chemicals. Here are some suggestions on how to apply the 3Rs principles (reduction, refinement, and replacement) for fish toxicology tests, some of which include: using fewer fish, performing fewer repetitions, use of model fish species and more sensitive fish, no use of endangered species, performing limit test before the main test, performing range-finding test with a higher distance of concentrations, using environmental concentrations and performing chronic instead of acute tests, reducing test time and early termination of the test if signs of considerable suffering are observed, replacing endpoints such as mortality with moribundity, using fish embryos instead of larvae and adult fish (and using dechorionated embryo instead of a complete embryo), using computational or in silico methods (such as QSAR and ECOSAR), using in vitro assays on fish cell lines, replacing fish with organisms such as microalgae and macrophytes and invertebrates such as snails, daphnids and brine shrimp, and finally toxicity evaluation of the active substances instead of the various formulations made from them.
