Fish may respond to different social situations with changes in both physiology and behaviour. A unique feature of fish is that social interactions between males and females strongly affect the sexual characteristics of individuals. Here we provide the first insight into the endocrine background of two phenomena that occur in mono-sex groups of the black molly (Poecilia sphenops): masculinizati...

Androgen administration has been widely used for masculinization in fish. The mechanism of the sex change in sexual fate regulation is not clear. Oral administration or pellet implantation was applied. We orally applied an aromatase inhibitor (AI, to decrease estrogen levels) and 17α-methyltestosterone (MT, to increase androgen levels) to induce masculinization to clarify the mechanism of the s...

In the tilapia Oreochromis niloticus, sex is determined genetically (GSD), by temperature (TSD) or by temperature/genotype interactions. Functional masculinization can be achieved by applying high rearing temperatures during a critical period of sex differentiation. Estrogens play an important role in female differentiation of non-mammalian vertebrates. The involvement of aromatase, was assesse...