Fish is clearly regarded as the cheapest source of protein for man and other livestock, but fish farmers are constrained by massive mortality of fry and fingerlings due to helminth parasite invasion. Prevalence of helminthic parasite infection of two (2) commercially important and easily-culturable fish species of Nigeria (Clarias gariepinus and Tilapia zillii) was studied in relation to sex and fish age (length and weight). 51 samples of Claris gariepinus and 34 samples of Tilapia zillii in Chanchaga River were caught by the use of a trawling net over a period of 24 months (September 2014 and October 2016). Four (4) classes of parasites were encountered between Clarias gariepinus and Tilapia zillii as the two species were infected with similar parasites: Monogenea, Cestode, Nematodes, and Acanthocephala, although nematode parasites were by far the most abundant. The infection rates of both Clarias gariepinus and Tilapia zillii with helminth parasites were high as their percentage infection was 88.2 % and 91.2, respectively. Females were slightly more infected than the males for both fish species, although the difference was not significant (P < 0.05). Fishes of higher lengths and weight for both Clarias gariepinus and Tilapia zillii were more prevalent in parasitic infection (higher % infection) than their counterparts with lower lengths and weights (lower % infection). There were no striking differences between Clarias gariepinus and Tilapia zillii in terms of parasite representation, sex, and age parameters. This phenomenon may not be unconnected to the fact that both fish species shared similar environmental conditions, dietary composition, and feeding habits. This study recommends a change of feeding habits and dietary composition with age and immune system state in order to reduce the infestation of parasites with the goal of increasing field yield efficiency.