Effect of artificial photoperiod on the blood cell indices of the catfish, Clarias batrachus

Abstract

The present study is aimed to assess the influence of artificial photoperiod on the blood cell indices of an Indian catfish, Clarias batrachus(Linn.). Blood samples taken from adult fishes exposed to artificial photoperiod of 24L:0D and 0L:24D for a short period of 24 hrs, were analyzed for total RBC, total WBC, differential leukocyte count (DLC) and some physiological variables – glucose and chloride. The total RBC and WBC counts were unaffected by both the artificial photoperiod regimes. However, lymphopenia (p<.05) and neutrophilia (p<.05) were observed under 24L:0D photoperiod. Blood chloride levels were significantly higher (p<.05) in 24L:0D whereas blood glucose levels remained unchanged in both the photoperiod treatments. The 0L:24D photoperiod did not produce any significant change in the blood cell indices neither in the physiological variables. The findings indicate that exposure to continuous light for as short a duration as of 24 hrs elicits stress responses in the leukocyte profile of this nocturnal fish and highlights the role of leukocyte profile as potential stress biomarkers in vertebrates.