0.05). No significant difference was found in the prevalence of helminths in relation to size, however bigger sizes of S. clarias and C. nigrodigitatus were more parasitized. Pathological conditions such as lymphocytic infiltration, moderate disruption of muscular mucosa and intestinal villi, edema were found in infected fishes.]]> 0.05) in the mean total lengths, carapace lengths and rostral lengths between male to male and female to female specimens of the two prawns. Also, no significant variation (p>0.05) existed in their mean body weights, although specimens of M. vollenhovenii appeared more robust in body shape. Mean chela lengths (right and left) were higher for M. macrobrachion than for M. vollenhovenii. Meristic count of dorsal spines on rostrum ranged from 8-15 and 8-16 while that of ventral spines ranged from 3-7 and 3-8 for M. macrobrachion and M. vollenhovenii respectively. The results obtained in this study revealed that these prawns are easily separable based on their morphological traits. However, further study is recommended for their genetic characterization to validate their true existence as separate species.]]>