Given the vital role of thyroid hormones (THs) in vertebrate development, it is essential to identify chemicals that interfere with the TH system. Whereas, among non-mammalian laboratory animals, fish are the most frequently utilized test species in endocrine disruptor research, e.g. in guidelines for the detection of effects on the sex hormone system, there is no test guideline (TG) using fish as models for thyroid-related effects; rather, amphibians are being used. Therefore, the goal of …