Occurrence of regenerated tail in Indian freshwater spiny eel, Macrognathus pancalus Hamilton, 1822 (Teleostei: Mastacembelidae), in northern West Bengal, India

The ichthyofaunal diversity of the Karala River and its adjoining areas in the Jalpaiguri District of West Bengal was studied from February 2009 to September 2010. A total of 3 identified species of freshwater spiny eels belonging to the order Synbranchiformes were recorded from a total of 55 captured species. During the course of the study period, the researchers collected 3 specimens that showed nearly all of the important features of Macrognathus pancalus except for the caudal fin character. The caudal fin was entirely converged with the dorsal and anal fins. The soft dorsal fin ray characters and the number of free predorsal spines specify that they belong to Macrognathus pancalus Hamilton, 1822. They show this type of morphology due to the regeneration of the tail.