Effect of photoperiod and temperature on ovarian maturation in the small characid fish Cheirodon interruptus

ABSTRACT Cheirodon interruptus is a small characid widely distributed in South America and frequently used as bait. The harvesting of wild fish to supply the market has a significant environmental impact. The effect of photoperiod and temperature on ovarian maturation is assessed to evaluate its potential to manipulate reproduction. Fish were exposed to three treatments (in triplicate): (light hours: L/temperature: °C) 12 L/20°C, 24 L/20-25°C, and 9.8–13.3 L/20-25°C. Gonadosomatic index (GSI), plasma estradiol (E2), oocyte diameter, and vitellogenic oocyte percentage were estimated. Mean GSI, E2 values, oocyte diameter, and percentage were significantly higher in 9.8–13.3 L/20-25°C than in the other treatments, indicating ovarian maturation. In turn, these values were minimal in the 24 L/20-25°C treatment, revealing ovarian regression. These results suggest that in C. interruptus, the photoperiod is the primary driver of gonadal maturation and the temperature plays a secondary role. This study demonstrated that manipulation of ovarian development is possible through the design of photothermal regimes based on the winter-spring transition.