A total number of 400 Clarias gaiepinus were collected alive from several and various locations at El-Burullus Lake and Lake Nasser, to investigate the prevailing nematodes that infect this fish species from the two locations. Nearly all the examined fish were positive for one or more nematodes; four spp. of two families were identified from Clarias gaiepinus at El-Burullus Lake: Procamallanus laeviconchus, Paracamallanus cyathopharynx, Neocamallanus spp. (recovered from the gall bladder for the first time) and Terranova spp. larvae (recorded for the first time in Kafr El-Sheikh Governorate representing new locality record), one nematode from Clarias gaiepinus at Lake Nasser: 3rd stage larvae (L3) of Contraceacum spp. (has zoonotic importance). The prevalence of Procamallanus laeviconchus, Paracamallanus cyathopharynx, Neocamallanus spp. and Terranova spp. larva were 37.5%, 44%, 0.5% and 10% respectively, meanwhile the prevalence of L3 larvae of Contraceacum spp. were 100%. This study was planned to compare between the nematodes infecting Clarias gaiepinus from the two lakes evaluating clinical signs, postmortem examinations, parasitological examinations, seasonal prevalence and histopathological investigations of infected fish with different nematodes infestation. Clarias gaiepinus must be eviscerated as soon as possible after catching to prevent 3rd stage larvae of Contraceacum spp. in the abdominal cavity from liberating from their sheaths and attacking the fish musculature (the edible part in the fish) as well as,prevent Terranova spp. larvae in the gills from attacking another parts of the fish and thus prevent the transmission of the nematodes of zoonotic importance to the consumers.