The internship will take place in the Institute of Marine Sciences of Andalucía in Puerto Real Cádiz. The objectives of this program are focused on determining the function of several factors in the regulation of the initial stages of male and female gametogenesis in fish, using the European sea bass as model. In fish culture some important problems related to reproduction can be solved. One of these problems is precocious maturation when fish become sexually active before time of puberty, diverting energy to reproduction and reducing somatic growth.