ABSTRACT
The present study was undertaken to investigate the toxicological effect of ?uoride (as NaF) on chromatophores in skin of larvivorous fish, Poecilia reticulata Peters after chronic exposure. Guppy is supposed to be amongst the most colourpolymorphic vertebrates in the animal kingdom. Fish were exposed to three sub-lethal concentrations of Sodium fluoride viz. lowest (5.75 ppm), lower intermediate (7.18 ppm) and higher intermediate (9.58 ppm), which were selected on the basis of 96 hrs. LC value of 115 ppm. 50 Anomalous behavioral alterations observed in NaF intoxicated fish were restlessness, erratic swimming movement, periodic surface to bottom movement, recurrent surfacing activity, loss of equilibrium, amplified gulping and increased opercular activity were pragmatically seen. Significant variation in colouration was observed in all the experimental groups as compared to control. The melanophores showed notable pigment aggregation state and/or pigment dispersion state. Structurally, melanophores were distinguished into three types viz., reticulate, stellate and punctuate. The severity in distortion of structure and number of chromatophore increased with increasing concentrations of fluoride. Several distortions in morphology and even functional integrity of chromatophores when compared with the control group were observed, for instance, rupture of pigment cells accompanied by breakage in dendritic processes, conversion of one type of chromatophore into another type, augmentation and detachment between adjacent chromatophores, variation in number with complete loss of cellular activity. The derangement in structural integrity was observed to be dose dependent and increased with increasing concentrations of Sodium fluoride, thus making the fish unfit for survival. The attractive pigmentation of the male Guppy fish was abridged making them less attractive for their mate thus affecting reproductive potential of the fish.