Meristic variations and skeletal deformities in natural population of mahseer fish, Tor putitora (Hamilton, 1822).

Skeletal deformities seriously relegate the biological performance of fish. The frequency of occurrence of different types of meristic variations and skeletal deformities were seen in the population of mahseer fish, Tor putitora, in two main reservoirs; Korang Stream, Islamabad and Dhobi Ghat Stream, Hassan Abdal. A total of ninety-five fish were caught randomly, forty-five from the unpolluted Korang Stream and fifty from the polluted Dhobi Ghat Stream by cast nets from February to July, 2009. Radiographs and dry skeletal preparation techniques were used to record meristic variations and skeletal deformities and describe various types and frequency of appearance. Deformities were studied under categories, Highest Frequency of Occurrence (HFO), Normal Frequency of Occurrence (NFO) and Lowest Frequency of Occurrence (LFO). In the deformed fishes, significant (p<0.001) anomaly was noticed in nineteenth to twenty second and forty one to forty third (p<0.05) vertebrae of the vertebral column. Deformities scoliosis (C2, 5.26%), platyspondyly (C5, 11.27%), and abnormal neural spine (TC25, 13.53) appeared to affect 70%, 60% and 50% of the deformed individuals respectively. This study concluded that skeleton deformities in T. putitora population in the laundry waste water of Dhobi Ghat Stream have relevance with detergent waste, as a possible causative agent.