Water Temperature and Photoperiod

The reproductive process in teleost fish is controlled by the hypothalamic-pituitary-gonadal axis, being activated by external factors such as water temperature and photoperiod. However, most fish in captivity do not spawn due to blockages at different levels of the gonadal maturation process, particularly in rheophilic species such as pacu (Piaractus mesopotamicus). In this sense, different procedures are used in order to stimulate the reproductive processes of final oocyte maturation to ensure the production of fry. However, the gonadal maturation of females in captivity generally begins in December, determining that the fattening of juveniles begins in January, thus losing much of the optimal growth temperature of the fry. In order to evaluate the effect of manipulating pond temperature and photoperiod on gonadal development in captive pacu females, four experimental treatments were proposed: T1: (Control), T2: (photoperiod) artificial light, T3: (temperature) greenhouse, and T4: (combined) photoperiod and temperature.