The objective of this work is to study the environmental and biological factors
affecting metacercarial infections in O. niloticus from brackish water, Ismailia, Egypt.
Fish were collected monthly during the period from March 2009 to February 2010
from two sites in El Sayadeen pool at Ismailia. Nine different trematode metacercariae
and undifferentiated cyst were recovered from O. niloticus fish. The identified
metacercariae were Euclinostomum sp., Pygidiopsis sp., Prohemistomum sp.,
Phagicola sp., Bolbophorus sp., Stictodora sp., and Haplorichis sp. The total
prevalence was higher in site 2 (75.44%) than site 1 (71.41%). The highest infection
was recorded in winter (75%), and the lowest in spring (24.67%). Infection was the
highest (76.86%) in the largest fishes in weight and size. Infection was higher in
female fish (77.57%) compared to males (70.73%). Prevalence, intensity and
abundance of each metacercaria species showed different responses to the considered
factors.