Ages at maturation of tropical freshwater eels, Anguilla bicolor bicolor and A. bengalensis bengalensis

Freshwater eels are one of the world’s most valuable cultured fish species. However, there is little information available on the biological characteristics of tropical anguillid eels genus Anguilla in the silver (maturation) stage even though these tropical eels account for two-thirds of all species in the genus. In order to understand the life history of tropical anguillid eels, Anguilla bicolor bicolor and A. bengalensis bengalensis which are found in Malaysian natural waters, age at maturation was studied. Their total length, body weight and maturation were significantly increased and advanced as their age became older. The ages at maturation (stages IV and V) of A. bicolor bicolor and A. bengalensis bengalensis ranged from 5.5 to 8.5 years and from 6.5 to 10.5, respectively. Ages of maturation in the tropical eels were earlier than that of other temperate eels A. anguilla, A. rostrata, A. australis and A. dieffenbachii, reported previously, although it was similar to that of the temperate eel A. japonica. The higher growth rate found in the tropical eels associated with the tropical habitat environment might induce the earlier maturation than the temperate species