LÄÄNE-EESTI VETE LESTA
female parasite attains gravidity or only as paradefinitive fish in which the nematodes
may become mature but are unable to produce eggs. Under European conditions, the
principal definitive hosts of R. acus are pike and trout (Moravec, 1994).
Some parasites found in flounder have a detrimental effect on the host. Species such as
D. spathaceum (the second most abundant parasite found) and P. laevis are well known
pathogens of flounder and other fish. D. spathaceum matacercariae infect the lens of
fish, causing blindness and a subsequent inability to find food.
P. laevis can cause mass invasions. The fish intestine shows gross lesions and other
organs can be damaged too.
A. anguillae have also been found in flounder before, but this thorn-headed worm
infects mostly predatory fish.
Tapeworm S. pungitii plerocercoid stage is common in stickleback (three-spined
stickleback and nine-spined stickleback). The plerocercoid in flounder indicates that
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