Mode of sexual differentiation and its influence on the relative sensitivity of the fathead minnow and zebrafish in the fish sexual development test.

Exogenous treatment of fish with natural sex hormones and their mimics has been shown to influence gonadal differentiation resulting in biased phenotypic sex-ratios. This has lead to the development of the Fish Sexual Development Test (FSDT) as a method for the detection of endocrine active chemicals. Proposed test organisms include the medaka, zebrafish (ZF) and stickleback, although the guideline also allows for inclusion of species such as the fathead minnow (FHM), provided the test duration allows for sufficient sexual differentiation.