The objective of this work is to study some environmental and biological
factors affecting metacercarial infections in Tilapia zilli from two sites at Lake
Timsah, Ismailia, Egypt. Fish were collected monthly from two sites during a period
from March 2009 to February 2010. Fish length and sex were determined. Five
different trematode metacercariae were recovered from T. zilli fish, namely,
Euclinostomum sp., Pygidiopsis sp, Phagicola sp., and Stictodora sp. and some were
undifferentiated. Infection was higher in site 2 (42.4%) than site 1 (32.59%). The
highest infection was recorded in winter (79.76%), and the lowest in spring (9.52%).
It was the highest (40.51%) in medium-sized fish. Males were more infected (38.93%)
as compared to females (30.04%). Prevalence, intensity and abundance of each
metacercaria species showed different responses to the considered factors as discussed
in this work