Effects of Photoperiod on Embryos and Larvae of Tawny Puffer, Takifugu flavidus

To determine the optimal condition of photoperiod for embryo development and larval culture of tawny puffer, Takifugu flavidus, the effects of photoperiod on egg hatching and the growth and survival of larvae from 3 to 23 d after hatching (dah) were assessed. The results show that photoperiodic responses varied with the developmental stage during the early development of tawny puffer. Photoperiod did not significantly affect the hatch rate, viability of 24 h post‐hatch larvae, and total mortality rate of tawny puffer embryos; however, it affected the incubation period, which significantly increased with increasing photoperiod from 6 to 24 h. The shortest incubation period was predicted to occur at 3.56 h day length from the quadratic relationship. However, photoperiod strongly affected the growth and survival of the tawny puffer larvae from 3 to 23 dah. Increasing the day length resulted in improvement of the larval growth and survival within the 0–12 h day length range; however, beyond the 12 h day length, a longer day length was not beneficial, and a 24 h continuous light had a negative effect on growth. From the quadratic relationships, the highest growth and survival rates were predicted to occur at 14.16 h and 17.74 h day length, respectively. Therefore, the optimal photoperiods for tawny puffer embryos and larvae were 3–6 and 12–18 h day length, respectively. The results of this study are useful in increasing the production of the species during incubation and larval culture.