Based on the parasitological examination of three hundred and twenty one specimens of Tilapia zillii (n=321), thirty three nematode species of the genus Cucullanus Muller 1777 were recorded. The fish species had overall prevalence of
9.6%. The female specimens had a prevalence of 11.8% (n=110 (18) 11.8%), while the male specimens had a slightly lower prevalence of 8.5% (n=211 (18) 8.5%). The nematode Cucullanus sp. was collected from the intestine of the fish host. SEM description of the recovered Cucullanus sp. shows some distinguishing features which place it apart from most of its congeners. The submedian papillae were located on the cuticle, single amphid in between the two upper submedian papillae, short spicule and 23 upper teeth and 34 lower teeth on the dorsoventrally elongate mouth.
The thistological sections of the parasitized host revealed marked sloughing of cells into the lumen and intraluminal adult nematode mixed with necrotic debris.