The demand for fish as a source of protein is on the increase. However,
sustainable productivity by fish farmers is constrained by parasitic infections. Thus, an investigation was conducted on the prevalence of helminth parasites in some commercially important fish species of River Anambra, Nigeria. A total of 521 fishes belonging to 6 families (Claroteidae, Synodontidae, Mormyridae, Osteoglossidae, Bagridae, and Clariidae) and 20 species caught with hooks, nets, and local traps were examined using standard parasitological techniques. The
overall prevalence was 23.80%. Fish samples belonging to 6 families had the following prevalence of infection: Bagridae (0.00%), Clariidae (2.11 %),
Claroteidae (1.53%), Mormyridae (0.0%), Osteoglossidae (14.97%) and
Synodontidae (5.18%). Helminth parasites recovered were: Weyonia species (4.65%), Weyonia youdeowii (15.97%), Weyonia synodontis (3.33%), Sandonella sandoni (37.41%), Polyonchobothrium clarias (17.98 %), Plerocercoid larva (13.33%) and unidentified cestode (35.47%) (Cestoda); Emoleptalea species (4.65%) (Trematoda); Procamallanus laeviconchus (2.72%), Dujardinascaris species (1.36%), Spirocamallanus species (3.99%) (Nematoda); Neoechinorhynchus species (24.61%), Tenuisentis niloticus (34.62%) and unidentified acanthocephalan (6.25%) (Acanthocephala). Weyonia species, Weyonia youdeoweii, and W. synodontis were recovered from synodontids only. Acanthocephalan, cestodes, nematodes and trematodes were found in decreasing order of abundance. The presence of trematode Emoleptalea sp in Clarias gariepinus is a new host record of the parasite for the geographical area.