OECD 240 Medaka Extended One Generation Reproduction Test (MEOGRT)

The Medaka Extended One Generation Reproduction Test examines the effect of chemicals on multiple generations of fish and is usefull to detect chronic effets of endocrine disruptors. Potential adverse effects on population relevant parameters are in the focus of this study as well as mechanistic information e.g. androgenic or oestrogenic activity.

Test Organism

  • Oryzias latipes (Japanese Medaka)

The Japanese Medaka has a short life-cycle and it is possible to detect his genetic sex. The identical test design is not applicable for other species.



Course of the test

Male and female fish are exposed in a dose-response design to a geometric series of five chemical concentrations. The highest test concentration should not exceed 10% of the LC50.

The test starts with sexually mature breeding pairs (F0), each pair in a separated tank.
After spawing of the adults, the F1 generation is exposed for 15 weeks including a reproductive phase, which should take place from week 12 to week 14.

The developing F2 generation is monitored for two weeks post fertilisation.

Total test duration is about 19 weeks. An interim sampling is made in week 9 to 10 for developmental endpoints.



  • Fecundity, fertility, hatching, growth, survival, behaviour, Vitellogenin, sexual phenotypic markers, histological evaluations and genetic sex determination
  • statistical evaluation, ECx calculation, NOEC/LOEC determination


Guidelines and literature

  • OECD Guideline for Testing of Chemicals, No. 240: Medaka Extended One Generation Reproduction Test (MEOGRT).