Testing acute toxicity in the embryo of zebrafish, Brachydanio rerio, as an alternative to the acute fish test: preliminary results

By Schulte, C. - Nagel, R.

Acute toxicity testing in fish is a standard method used in estimating the influences of chemicals on aquatic vertebrates. The ecotoxicological data obtained from acute toxicity tests in fish are however, not sufficiently reliable to justify the continued use of this test. Fertilised eggs of zebrafish (Brachydanio rerio) were used to test the acute toxicity of chemicals. They were chosen because the development of B. rerio has been studied extensively and information already exists concerning the normal development of this species. The following parameters of the development of B. rerio were observed: coagulation of the egg, gastrulation, number of somites, movement, development of organs, pigmentation, heartbeat and circulation. Some of these toxicological endpoints indicate lethality. In addition, various interactions between the test chemical and the embryos can be measured by investigating these parameters. Six chemicals (2,4-dinitrophenol, 4,6-dinitro-o-cresol, malathion, carbaryl, phenol and 4-nitrophenol) were selected for testing in the embryos of zebrafish within the first 48 hours of their development. The toxicities of the test chemicals to zebrafish embryos were compared with their acute toxicities to adult fish. Further investigations with more chemicals are in progress. The effective concentrations (EC50) and the lowest effect concentrations (LOEC) investigated in this preliminary study were comparable to the LC50 values for adult fish. The use of this test system as an alternative method to testing toxicity in adult fish is discussed.