Impact of Photoperiod as an Environmental Cue on Growth and Reproductive Performance in the Red Eyed Orange Molly (Poecilia sphenops)

Abstract

Light is a major environmental factor that synchronizes all life-stages of fish development. The objective of this research is to enhance the growth and reproductive performance in the test fish, Red eyed orange molly (Poecilia sphenops) live-bearer fish, by exposing to standardized manipulated photoperiods. In the present study, the growth and the gonadal development of the test fish of an average initial weight (0.5 ± 0.01 g) and of an average total length (3.5 ± 0.01 cm) is exposed to two photoperiods: (18 Light:6 Dark) and (10 Light:14 Dark) at constant light intensity (1500 lx) for a period of 60 days were investigated. During the long day photoperiod (18L:6D) significant differences in growth parameters such as, weight gain (2.2 ± 0.07%), feed conversion ratio (8.9 ± 0.004) and specific growth rate (1.3 ± 0.02% day−1) are observed when compared with short day photoperiod (10L:14D) and control group. The mean gonadosomatic index in female (29.26 ± 1.09%) and male fish (2.2 ± 0.2%) was found significantly higher in long-day photoperiod followed by short day photoperiod. The result confirmed that manipulated long-day photoperiod induced the somatic growth and enhanced the gonadal development in P. sphenops without causing mortality.