ABSTRACT
A survey of the helminth fish parasites was carried out at Ogba River, Benin City, Edo State. A total of 562 fishes belonging to 12 families, 17 genera and 19 species were examined for parasites.
Routine body measurements of fish, such as standard length, total length and weight, were determined. Thereafter, fishes were examined for both external and internal parasites. Of the total number examined, 36.12% were infected with various species of helminth parasites. Of the twelve (12) fish families examined, only six (06) were infected with parasites. The following helminth parasites were recovered: Caryophyllaeides sp, Crescentovitus sp, Bialovarium sp, Lytocestus sp, Monobothrium sp, Stocksia sp, Cucullanus sp, Procamallanus laeviconchus, and Spinitectus sp. Cestodes accounted for 78% of the infection, while the nematodes accounted for 22%. The main location of parasite occurrence in fish was the intestine. Sex did not influence the degree of helminth parasite infection in fishes. Small sized and younger fishes were mostly infected. Five (05) of the parasites (Stocksia sp, Monobothrium sp. Bialovarium sp, Crescentovitus sp and Caryophyllaeides sp) were new parasites recorded in the fishes of Ogba river.
Some new hosts were encountered in the present study. The cestode, Lytocestus sp, was recorded in the following hosts, Auchenoglanis occidentalis, Chrysichthys nigrodigitatus, Clarias macromystax, Synodontis eupterus and Synodontis nigrita. Also, the present study revealed new host records for the following nematode parasites: Parachanna obscura (Cucullanus sp, Procamallanus laeviconchus and Spinitectus sp) and Papyrocranus afer (Spinitectus sp). Although the nematode, Spintectus sp, was reported earlier in Nigeria to infect Papyrocranus afer. The present study shows that Parachauna obscura is its new host.
The occurrence of various parasites in a wide range of fish families and species in this study showed that there was no strict host specificity among the parasites. The high condition factor values recorded in this study proved that the parasite infection had negligible effect on the fishes of Ogba river.
