This study is one of series of paper expected to occur in this journal (Part of my PhD work Moi University2014-17). The study conducted between January 2016--June 2016 involved three counts, Kirinyaga, Kisii, and Uasin gishu of Kenya, with the aim to investigate problems of stunted and mortality of 520 fishes of these two species of fresh water from farmer ponds were randomly sampled and examined for internal cestode parasites. 100 fish were C. gariepinus and 420 O. niloticus. These specimens were killed by scissors or a knife and then dissected internal organs placed in Petri dish mixed well with sodium chloride solution different parasites observed and identified using common characteristics and standard keys. The over roll results show that 240 (46.2%) of the total fish examined were infected by different parasites. C. gariepinus had a higher infection rate 55(55.0%) out of the 100 fish sampled compared to O. niloticus 185 (44.1%) of the 420 fish sampled. Prevalence and diversity of internal parasites. Diphyllobothrium latum (34.59%), Proteocephalus spp (49.62%), Caryophyllidea spp(13.53%) and mixed infection (2.26%) Statistically Significance was tested at 0.05,The study findings show t that there was a significant relationship ( p=0.0002) between the type of fish and the number of parasites Also insignificant Relationship observed between internal cestode parasites and sampled fish on length (0.06657), weight(0.1690) and sexes (0.3668). The study concluded that the C. gariepinus are more attacked by internal cestode parasites compared O. niloticus. Our study suggest that farmers to keep more species with higher tolerance with parasites.