The western mosquitofish (Gambusia affinis affinis): a new laboratory animal resource for the study of sexual dimorphism in neural circuits.

The western mosquitofish (Gambusia affinis affinis) is a useful model for the study of sexual dimorphism and the neural circuits associated with sexual differentiation. This is largely because of its anal fin, which undergoes radical postnatal transformation in males. Understanding the neural mechanisms involved in this process may also help elucidate basic principles of the nervous system. The authors describe the mosquitofish as a model for research and present guidelines for the care and use of this species.