Effects of Photoperiod Regimes on Growth performance of Heterobranchus bidorsalis (Geoffrey St. Hilaire, 1809) fingerlings under Laboratory Conditions.

Abstract

Environmental factors are known to influence growth and survival of aquatic organisms. Varying intensities of light can be of great advantage to catfishes This research investigated the effects of photoperiod regimes on growth performance of Heterobranchus bidorsalis fingerings under controlled environment. A total of ninety (90) samples of the fish were acclimated for a period of 14 days during which they were fed to satiation twice daily. The experimental set-up consists of three treatments 3 replicates in each case. Treatment 1 is the control; 12 hours light and 12 hours dark, treatments 2 and 3 were subjected to 6 hours light and 24 hours total darkness, respectively with each tank stocked with 9 fish samples. The aquarium tanks were routinely placed in a simulated dark room and subsequently natural light in accordance to the duration of exposure desired for a period of 12 weeks. The physico-chemical parameters of the test media were taken according to standard methods. The growth parameters (lengths and weight) of the fish were taken on a weekly basis and the varying morphological pigments were noted at the end of the experiment. The weight gain and specific growth rate were also calculated. The resulting data were subjected to one way analysis of variance. From the results: the highest growth performance of the fish was recorded in T3, followed by T1 while lowest growth performance was recorded in T2. Better feeding efficiency was also influenced by photoperiods as highest feeding rate was recorded in T3. Changes in body pigmentation was more prominent in T3 as H.bidorsalis fingerlings exposed to this regime became black and darker in appearance in comparison to T1 samples which were lighter in complexion. Consequently, it is believed that subjecting H.bidorsalis fingerlings to 00L: 24D photoperiod regime by fish farmers can lead to improved farm yield and profits to the farmers.