The effect of different photoperiod on growth and survival in guppy larvae (Poecilia reticulata)

Growth in animals is controlled by genetic, environmental, and nutritional factors, including external factors (temperature, pressure, salinity, and light) in the evolution of cold-blooded animals. In this study, the effects of three different light treatments on the growth and survival rates of guppy larvae (Poecilia reticulata) were investigated. The larvae of this species with an average initial weight of 0.015 g for a month were exposed to 12 h light and 12 h dark (12 L:12 D) as control treatment, 24 h light without darkness (24 L:0D) and 24 h dark without light (0 L:24 D). At the end of the experiment, the larvae affected by the 24 h light treatment had the highest growth, body weight gain and specific growth rate, which showed a significant difference with the 24 h dark treatment (P<0.05) however, the effects of the photoperiod treatments on larval survival were not significant (P<0.05). The results of this study showed that the photoperiod is one of the factors influencing the growth rate of this species and with increasing the photoperiod the growth will be better.