Merck Manual

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Protistan Parasites of Fishes

Protistan Parasites of Fishes

Parasites

Tissue

Susceptible Species

Signs

Diagnosis

Treatment

External ciliates (motile)

Ichthyophthirius (FW), Cryptocaryon (SW)

Gills, skin, fins

All

White spot disease; no spots visible if on gills only

Wet mount

FW—formalin, CuSO4; SW—formalin, Cu2+, decreased salinity, chloroquine (efficacy not completely demonstrated)

Trichodina (FW, SW), Chilodonella (FW), Brooklynella (SW)

Gills, skin, fins

All

High respiration rate, piping, excess mucus, flashing, loss of condition

Wet mount

FW—formalin, CuSO4; SW—formalin, Cu2+

Tetrahymena (FW), Uronema (SW)

Skin, eye, muscle

All (“guppy killer”)

Mucus, flashing, intra-ocular lesions, exophthalmos

Wet mount

External as above; improve sanitation Internal: no treatment

External (sessile)

Ambiphyra, Apiosoma, Epistylus

Gills, skin, fins

Primarily pond fish

Excess mucus, flashing, piping, loss of condition

Wet mount

Formalin, KMnO4, CuSO4 Management—decrease crowding, correct sanitation

External flagellates

Ichthyobodo, Cryptobia (see also Internal flagellates)

Gills, skin, fins

All

Blue slime, flashing, piping, excess mucus, loss of condition

Wet mount

Formalin, CuSO4, KMnO4, salt

External dinoflagellates

Piscinoodinium (FW), Amyloodinium (SW)

Gills, skin

Tiger barbs, many marine fishes, including clownfish and red drum

Mortality, lethargy, piping; “velvet” (if on skin)

Wet mount

Copper sulfate, chloroquine (nonfood fish only); freshwater dips for marine food fish

Internal flagellates

Spironucleus

Intestine

All cichlids, bettas, gouramis, other aquarium fishes

Weight loss (anorexia), mortality of fry and juveniles

Wet mount

Metronidazole (nonfood fish only)

Cryptobia iubilans

Stomach

African cichlids

Extreme weight loss, anorexia

Wet mount, histology

None; management—correct sanitation, feeding, stocking density, cull affected fish

Trypanosoma

Blood

Wild-caught Ioricariids

Anemia, mortality

Wet mount

None

Coccidia

Various genera

Intestine

Multiple

Weight loss, mortality

Histology

Sulfamethazine (efficacy questionable)

Note: FW = freshwater; SW = saltwater