Parasites of Fish from the Great Lakes - Great Lakes Fishery ...

Pathogenic Parasites
Protozoans
Ichthyophthirius multifiliis can cause weight loss and mortality in fish (Davis 1944; Elser 1955;
and Allison and Kelly 1963). Trichodina spp. may cause severe hyperplasia of the gill lamellae
and inflammation of the ureters (Richardson 1938; Davis 1947; Hoffman and Lom 1967). Several
species of myxosporidians (Myxidium spp., Henneguya spp., Myxobolus spp., and Thelohanellus
notatus) were found in the gills, kidney, muscle, mouth tissue, connective tissue, skin, cartilage,
fins, heart, mesentery, and bile ducts, and can damage their fish host (Dogiel et al. 1958;
Reichenbach-Kline and Elkan 1965; Reichenbach-Klinke 1973; Edwards et al. 1977). Glugea
cepedianae, G. hertwigi, and G. pimephales can damage the mesentery and internal organs of
fish. The gonads of Osmerus mordax have been damaged by G. hertwigi (see Dechtiar 1972a;
Nepszy et al. 1978; Putz et al. 1965).
Digenetic Trematodes
Adults of several species of Crepidostomum, Acetodextra amiuri, and Sanguinicola occidentalis
can cause inflammation and lesions of the intestine, reproductive system, and circulatory system
in their fish hosts (Davis 1937; Perkins 1951, 1956; Wales 1958b). Of the larval digenetic
trematodes, Clinostomum complanatum, Centrovarium lobotes, Crassiphiala bulboglossa,
Posthodiplostomum minimum, Uvulifer ambloplitis, Apophallus brevis, A. venustus,
Ichthyocotylurus diminuta, I. intermedia, Ichthyocotylurus sp., and Tylodelphys scheuringi can be
considered pathogens to fish as well as play a role in anglers discarding infected fish because of
unsightly parasites (Kozicka 1958; Meyer 1958; Wales 1958b; Bychovskaya-Pavlovskaya and
Petrushevski 1963; Dukes 1975). Smitherman (1968) demonstrated that fingerlings of Lepomis
macrochirus had a significant reduction in growth and increased mortality when infected with
more than 353 metacercariae of Posthodiplostomum minimum. The three species of Diplostomum
can possibly cause subcapsular cataracts, lens discoloration and blindness, exopthalmic condition,
and emaciation (Shariff et al. 1980). Crowden and Broom (1980) reported that Leuciscus
leuciscus heavily infected with Diplostomum spathaceum spent more time feeding but caught
fewer Gammarus, and spent more time in the surface water, which increased their vulnerability to
predators.
Monogeneans
The ancyrocephalids, Dactylogyrus spp., Diclybothrium armatum, Gyrodactylus spp., and
Tetraonchus monenteron can cause thinning of the epidermis of the gills, excessive mucus
production, epithelial hyperplasia, and can produce portals of entry for secondary fungal
infections (Mizelle 1938; Tripathi 1959; Dogiel et al. 1958; Prost 1963; Lester and Adams 1974;
Hoffman 1976; Wobeser et al. 1976; Cusack and Cone 1986).
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