Effect of temperature on gonadal differentiation and growth of Leporinus friderici

This study aimed to investigate the effect of temperature on gonadal differentiation, growth, survival, and sex ratio of reared at 25 °C or 29 °C from 50 to 240 days after eclosion (DAE) in a water recirculation system. A total of 110 fish at 50 DAE (6.7 ± 0.1 cm and 6.1 ± 0.3 g) were equally and randomly distributed in 10 boxes (90 L) (11 fish/box, 5 boxes/temperature). One fish from each experimental unit was randomly sampled at 50, 70, 90, 110, 130, 150, 170, 190, 210 and 240 DAE. Female gonadal differentiation started at 150 DAE (11.4 ± 0.0 cm and 16.4 ± 0.0 g) at 25 °C and at 170 DAE (10.7 ± 0.7 cm and 27.7 ± 8.5 g) at 29 ºC, while testes differentiation only occurred at 29 °C from 190 DAE (12.1 ± 0.0 cm and 38.0 ± 0.0 g). Of 50 fishes sampled in each condition, 17 (12 females and five males) and three (three females) displayed gonadal differentiation at 29 °C and 25 °C, respectively. Final biometric values at 29 °C were twice those obtained at 25 °C, reaching 13.9 ± 0.65 cm and 57.3 ± 10.12 g 11.2 ± 0.39 cm and 28.5 ± 2.95 g, respectively. While temperature clearly influenced gonadal differentiation and growth, it had inconclusive effects on sex ratio. The higher temperature (29 °C) has direct implications for the production of this species, as it accelerates growth without causing mortality.