Freshwater Fish Parasites Flashcards by Hayley Bird

Chilodonella

motile ciliate (protozoa)
Target: skin, fin, gills
Appearance: ovoid or kidney-shaped with bands of cilia along the long axis; dorsoventrally flattened; appears translucent
Movt: free-moving
Often causes fish to excrete excessive mucus
Tx: formalin bath/PI, acetic acid bath, KMnO4 PI, saltwater PI, Cu PI

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Gyrodactylid

Monogenean (metazoan ectoparasite)
Target: primarily skin and fish
Appearance: two pairs of anchor hooks, v-shaped “head”
Movt: free-moving, thorugh anchor end often attached to fish tissue
Live-bearer, may be able to see fully-developed embryo with hooks inside adult
Tx: formalin bath/PI, trichlorphon bath/PI, acetic acid bath, FW bath (SW fish), SW bath (FW fish), KMnO4 PI, Cu PI, Praxi bath/PI, mebendazole bath/PI, fenbendazole PI, chloramine-T bath

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Microsporidians

Protozoa
Target: any, common in muscle for some fish
Appearance: often see grainy-looking cysts first (parasites inside cyst); individual parasite shaped like egg or Dutch “wooden shoe”
Movt: not free-moving
Burst cyst to “free” individual spores for identification, direct fish to fish transmission in species studied
Tx: toltrazuril bath, fumagillin oral (disinfect and quarantine)

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Myxozoans

Protozoa
Target: any
Appearance: spores of different species vary greatly in shape and size, often see cysts first (parasites inside cyst), all spores have one to six polar capsules
Movt: not free-moving
Burst cyst to “free” individual spores for ID, in species studied, indirect life cycle involving oligochaete worm
Tx: fumagillin oral (disinfect and quarantine)

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Cryptobia iubilans

Flagellates (protozoa)
Target: stomach, may be present in other internal organs
Appearance: elongated to teardrop-shaped
Movt: free-moving, may appear to undulate
typically associated with granulomas in stomach, found only in cichlids to date, similar looking species found only externally on fish
Tx: formalin bath/PI

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Arugulus

“Fish Louse”

Brachiurans (Crustacean)
Target: skin, fin
Appearance: flattened, saucer shape, two suckers, two eeyspots
Mov’t: free-moving, ma glide over fish when feeding
Can be seen with unaided eye, common in koi and goldfish, sucks body fluids from host, egg-layer (requires multiple txs)
Tx: Trichlorphon PI, formalin bath, enamectin oral, biocontrol in ponds (mosquitofish)

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Epistylis

sessile ciliate (protozoa)
Target: skin, fin, (less commonly) gills
Appearance: elongated on stalks; forms colonies
Movt: not free-moving on fish, may see cilia move
often found in combo with Aeromonas sp.
Tx: salt baths, salt PI, systemic abx, resistant to formalin

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Spironucelus vortens*
“Hexamita”*

Flagellate (Protozoa)
Target: GI tract
Appearance: pear to barrel-shaped
Movt: free-moving, rapid and directed movement
common in cichlids, similar/related flagellates (“Hexamita”) seen in other fish groups
Tx: metronidazole oral/PI, secnidazole oral, magnesium sulfate oral, increase temp

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Ichthyophthirius multifiliis

motile ciliate (protozoa)
Target: skin, fin, gills
Appearance: amoeboid, C-shaped nucleus seen in “adults” only
Movt: free-moving, rolling, amoeboid motion
life cycle includes stages on and off fish
Tx: formalin bath/PI, Cu PI (less expensive), salt PI, increase temperature, transfer to new aquarium for 7d at 25C

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Ambiphrya

sessile ciliate (protozoa)
Target: skin, fin, gills
Appearance: barrel-shaped with row of oral and midline cilia
Movt: not free-moving on fish, may see cilia move
Tx: Formalin bath/PI, copper PI, KMnO4 PI, salt PI

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Piscinoodinium*
“Freshwater Velvet”*

Dinoflagellate (Protozoa)
Target: skin, fin, gills
Appearance: oval shape with amber color, “granular” interior; may see clear area near middle and one end of oval
Movt: not free-moving
most pathogenic to young fish; complex life cycle with stages on and off fish
Tx: saltwater PI

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Protoopalina symphysodonis

Flagellates (Protozoa)
Target: GI tissue
Appearance: spindle-shaped (rounded at one end, tapered at other end) or cylindrical; circular in cross-section; resembles a ciliate
Movt: free-moving
Usually commensal

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Ichthyobodo

(Formerly Costia)

Flagellate (Protozoa)
Target: skin, fin, gills
Appearance: teardrop-shaped
Movt: free-mvoing; corkscrew swimming pattern; may appear to flicker like flame
infected fish often secrete excess mucus
Tx: formalin bath/PI, KMnO4 PI, metronidazole oral, secnidazole oral, increase temperature, salt bath (FW fish)

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Capillaria

Nematode (Digenean)
Target: GI tract
Appearance: smooth, elongated worm; double-operculated barrel-shaped eggs amy be seen in females; may see egs only in fish tissues
Mov’t: free-moving, serpentine (snake-like) mov’t
direct life cycle, can spread directly from fish to fish
Tx: larvae-none, adult-fenbendazole, levamisole

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Digeneans Trematodes

(“Digenes”, “White Grub”, “Yellow Grub”, or “Black Grub”)

Target: metacercariae (juvenile encysted stage) in any internal or external tissue (if fish are IH), adults usulaly in gut lumen (if fish are FH)
Appearance: metacercariae seen as nodules/masses ~1-4 mm in length, adults ~1-5 mm in length, adults and jeveniles have visible oral and ventral suckers but no segments or chitinous hooks
Movt: adults free-moving, may see movement inside metacercariae cyst
Indirect life cycle often involving bird, snail and fish; fish usually IH; if in cyst, burst cyst to “free” individual for ID
Tx:
- larvae: prevention (keep infected birds and mammals away), disinfect and quarantine, Baluscide, Cu PI, prazi injection, PI

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Contracaecum

Nematode (Digenean)
Target: body cavity, liver, muscle, heart, swim bladder
Appearance: grossly visible, often seen coiled (encysted)
Mov’t: mov’t usually not seen in fish
Indirect life cyclle includes birds and invertebrates
Tx: larvae-none, adult-fenbendazole, levamisole

Dactylogyrid

Monogenean (metazoan ectoparasite)
Target: primarily gills
Appearance: two to four eye spots, one pair of large anchor hooks, scallop shaped head
Movt: free-moving, through anchor end often attached to fish tissue
Egg layer
Tx: formalin bath/PI, trichlorphon bath/PI, acetic acid bath, FW bath (SW fish), SW bath (FW fish), KMnO4 PI, Cu PI, Praxi bath/PI, mebendazole bath/PI, fenbendazole PI, chloramine-T bath

Ergasilus

Copepod (Crustacean)
Target: primarily gills
Appearance: conical, segmented body with grasping antennae
Direct life cycle, often incidental on fish but modified antennae used to grasp fish can cause severe, localized damage and infection
Tx: difluorbenzuron, lefluobenzuron

Eustrongylides

Nematodes (Digenean)
Target: internal tissue
Appearance: grossly visible; coiled, reddish worm (encysted)
Mov’t: movement usually note seen in fish
Fish is IH, DH is wading bird, oligochaete worm required as IH in some species
Tx: larvae-none, adult-fenbendazole, levamisole

Camallanus

Nematode (Digenean)
Target: intestinal tract, all other organs
Appearance: smooth, cylindrical, elongated, reddish thread-like worm
Movt: free-moving, serpentine (snake-like) mov’t
often protrudes from anus, live-bearer, larvae may be seen in adult, indirect life cycle (requires invertebrate IH)
Tx: larvae-none, adult-fenbendazole, levamisole (“leavin’ my a’hole”)

Lernaea

“Anchor Worm”

Copepod (Crustacean)
Target: skin, fin
Appearance: long, narrow; “anchor” at one end imbeds into fish; pair of egg sacks often seen at end opposite of anchor
Mov’t: generally seen fixd (attached with anchor) on fish
Only females are parasitic; can cause secondary bacterial infections due to wound from anchor; common in koi, goldfish and golden shiners
Tx: difluobenzuron

Apiosoma

sessile ciliate (protozoa)
Target: skin, fin, gills
Appearance: vase-shaped with oral cilia
Movt: not free-moving on fish, may see cilia move
Tx: formalin bath/PI, copper PI, KMnO4 PI, salt PI

Trichodina

Motile ciliate (protozoa)
Target: skin, fin, gills
Appearance:“flying saucer” or “scrubbing bubbles” shape
Movt: free-moving, whirling motion
Tx: formalin bath/PI, KMnO4 PI, saltwater bath (FW fish), freshwater bath (SW fish), Cu PI, acetic acid bath

Capriniana

sessile ciliate (protozoa)
Target: gills
Appearance: amorphous shape with cilia which stick up like pins in pin cushion
Movt: not free-moving on fish
Tx: formalin bath/PI, copper PI, KMnO4 PI, salt PI

Tetrahymena

motile ciliate (protozoa)
Target: skin, fin, gills, eyes, internal organs
Appearance: ovoid with evenly distributed cilia
Movt: free-moving
Commonly found on dead fish or detritus
Tx: formalin bath

Coccidia

Protozoa
Target: intestinal tract (most common), may be present in other organs
Appearance: egg-shaped, clear oocyst; typically contains four sporocysts
Movt: not free-moving
May or may not cause significant disease
Tx:?