Improvement in hatching rates in the Japanese eel Anguilla japonica by the control of rearing temperatures in the late stage of maturation in the female parents

► A temperature of 18 °C helps improving hatching rates of artificially matured eels. ► The hatching rates at 20 and 18 °C were 16.6% and 45.9%, respectively. ► At 18 °C, rapid progression of oocyte development was prevented. ► At 18 °C, the optimal time interval for ovulation induction was prolonged. ► At 18 °C, the probability of optimal timing of ovulation induction increased.