Length-Weight, Length-Length Relationship of the Spiny Eel, Macrognathus pancalus (Hamilton ۱۸۲۲) sampled from Ganges and Brahmaputra river basins, India

The freshwater spiny eel, Macrognathus pancalus is an inland water teleost fish commonly known as barred or striped spiny eel found in Asia. The sampling areas were selected which are spatially and geographically different and characterized by different environmental conditions in order to elucidation of ecotype. A total ۳۴۵ specimens were collected from the sampling sites during January ۲۰۰۸ to December ۲۰۱۰. The weight of M. pancalus in the present study nearly the cube of its length in all cases as the values of regression coefficient ‘b’ were found to be close to ۳. The length weight relationship indicated the isometric growth in all the samples of striped spiny eel collected from different environmental condition. The coefficient of regression ‘b’ were more in the riverine population (۳.۱۷±۰.۰۸) as compared to the populations of a large lake i.e. Beel (۲.۸۵±۰.۱۳). The coefficient of determination, (r۲) in all the cases was highly significant (p< ۰.۰۰۱). The relative condition factor (Kn) were also calculated and the average of condition factor in riverine and beel populations of spiny eel were found to be ۰.۵۰±۰.۰۹, and ۰.۴۷±۰.۰۵, respectively. The length-length relationship was highly correlated (r۲= ۰.۹۹ at P<۰.۰۰۰۱) for all the individuals of both habitats. A significant size difference was also noted between the river basin populations of M.pancalus. In the present study the length-weight, length-length relationship of M.pancalus in two different river basins was compared.

Keywords:

Macrognathus pancalus , Length-weight relation , Condition factor