Fish egg test

DIN EN ISO 15088

Fertilised egg
8-cell stage
Embryo 24 h
Embryo 48 h
Coagulated egg (lethal)


The fish egg test with the zebrafish (Danio rerio) is designed to determine acute toxicity of water constituents and effluents on embryonic stages of fish. It was established as an alternative approach to classical acute fish toxicity testing and is considered to be a “sub-organismic” test, since the central nervous system is not yet developed during the test period.


Newly fertilised zebrafish eggs are exposed to effluents for a period of 48 h. Death of embryos and certain defined disturbances of embryonic development, which finally lead to death, are considered effects. At 24 and 48 h, four apical observations are recorded as indicators of lethality:

  • coagulation of fertilised eggs,
  • lack of heartbeat,
  • lack of detachment of the tail-bud from the yolk sac,
  • lack of somite formation (criterion of wíthdrawn DIN 38 415-6, is only recorded).

At the end of the exposure period, acute toxicity is determined based on a positive outcome in any of the four apical observations recorded and the lowest ineffective dilution (LID) (dilution at which 90% of the fertilised eggs survive) is given as test result.