Fish

Question 1

Ichthyophthirius multifiliis

Answer 1

Disease Name: “Ich” or Freshwater white spot disease
Type: Obligate cilliate
Site: Small, raised, white lesions on skin, fins, and gills
Unique features:Large, holotrich ciliate with a characteristic C shaped macronucleus.
Treatment: Various water additives such as formalin, potassium permanganate, increase NaCl in tank, Copper sulfate

Cryptocaryon irritans is the marine variant

Question 2

Cryptocaryon irritans

Answer 2

Disease Name: Marine white spot disease
Type: Obligate cilliate
Site: Small, raised, white lesions on skin, fins, and gills
Unique features:Large, holotrich ciliate without a characteristic C shaped macronucleus.
Treatment: Various water additives such as formalin, Chloroquine decrease NaCl in tank, Copper sulfate

Ichthyophthirius multifiliis is the freshwater variant

Question 3

Tetrahymena

Answer 3

Disease Name: tetrahymeniasis
Type: Freshwater, Cilate, free living
Site: typically external infections on skin and gills, sometimes systemic. More of an opportunist than a true parasite.
Unique features:Small cylindrical, pyriform shaped ciliates
Treatment: Correct sanitation

Uronema is the marine variant

Question 4

Uronema

Answer 4

Disease Name: n/a
Type: Marine, Cilate, free living
Site: Can cause severe systemic infections, especially in stressed or injured fish (common in aquaculture and aquaria). Causes hemorrhagic lesions on skin, muscle, and internal organs.
Unique features:Small cylindrical, pyriform shaped ciliates
Treatment: Correct sanitation

Tetrahema is the freshwater variant

Question 5

Epistylis colisarum & E. lwoff

Answer 5

Disease Name: n/a
Type: Freshwater, Cilate
Site: Attach to the surface of epithelial layers of the skins and fins resulting in a localized skin lesion and mechanical disruption of osmotic regulation
Unique features: Sessile, peritrichous ciliate that divides by binary fission along the longitudinal axis, producing 2 daughter cells

epi- = “upon” or “on top of” (epí)
stylis = “pillar” or “column” (stylos) ➡️ “On a stalk” / “sitting on a column”

Question 6

Trichodina spp.

Answer 6

Disease Name: n/a
Type: Freshwater and marine, Cilate
Site: Infects the external surface of the of the skins, gills, and fins. Some species invade the urinary tract
Unique features: Flattened, circular, ciliated protozoan detected in wet mounts of skin biopsies and gill and fin snips. Identified by its prominent internal denticular (toothlike) ring (arrow) and ventrally located concave disk

epi- = “upon” or “on top of” (epí)
stylis = “pillar” or “column” (stylos) ➡️ “On a stalk” / “sitting on a column”

Trichodina means “Hairy toothed” — refers to the cilia (hair-like struct

Question 7

Trichophyra sp.

Answer 7

Disease Name: n/a
Type: Ciliate protozoan of freshwater fish worldwide
Site: Pincushion like ciliates attach to the epithelial surfaces if skin, fins, and gills
Unique features: Wet mounts of skin biopsies and gill snips. It has numerous structural tentacles. Usually found on pond reared fish.

phyra / phora = “bearing” or carrying

tricho- = “hair” (thrix, trichos)

Question 8

Amyloodinium ocellatum

Answer 8

Disease Name: Velvet or rust disease
Type: Flagellate protozoan in freshwater, brackish and marine fish
Site: Primarily causes irritation of the gill resulting in hyperplasia and fusion of gill laminae. Also attaches to skin and fins.
Unique features: Amyloodinium = “starch whirler,” named because the parasite’s cells stain strongly with iodine, indicating stored starch-like granules.

Question 9

Ichthyobodo necator

Answer 9

Disease Name: n/a
Type: flagellated protozoan (kinetoplastid) of freshwater fish
Site: Extremely pathogenic,especialy in young and older fish. Feeding stages attaches to the skin, fins, and gill causing irritation and hyperplasia of skin and fusion of gill lamellae

Question 10

Myxobolus spp.
Myxobolus cerebralis

Answer 10

Disease Name: Whirling disease
Type: Cnidaria (Myxosporea) of freshwater, brackish and marine
Site: Infection of salmonid with M. cerebralis may cause loss of melanophore control resulting in black tails or skeletal deformities from cartilage destruction. These parasites are typically found in the epithelial tissues of gills, skin or intestine, but may also invade muscle, cartilage and other internal organs

Question 11

Henneguya spp.
Henneguya ictaluri

Answer 11

Disease Name: “proliferative gill disease (PGD)” or “hamburger gills”
Type: Cnidaria (Myxosporea) of freshwater, brackish and marine
Site: Generally infects the epithelial tissue of the gils and skin but may also invade muscle and internal organs. Causes a hyperplastic reaction in epithelial cell of the gills causing severe bronchitis and respiratory compromise. Serious problem in commercial catfish industry
Unique feature: From Ictalurus, the genus of North American catfish (Greek ichtys = fish + ailouros = cat).

Question 12

Gyrodactylus spp.

Answer 12

Type: Monogenean
Site: Skin and fins
Unique features: Mostly freshwater and some marine. Viviparous

Question 13

Dactylogyrus spp.

Answer 13

Type: Monogenean
Site: Gills of freshwater fish
Unique features: Ovoviviparous

Question 14

Neobenedenia spp.

Answer 14

Type: Monogenean
Site: Skin, eyes and fins of marine fish
Unique features: Ovoviviparous

Question 15

Neascus spp.

Answer 15

Common name: Black spot disease
Type: Digenean trematode
DH: Piscivorous birds
1st IH: Freshwater snails: mainly Planorbidae (ram’s horn snails, e.g. Planorbella trivolvis, Helisoma spp.) and sometimes Physidae (Physa spp., Physella spp.)
2nd IH: Fish — skin, fins, and muscle tissues
Site: Black cysts on the skin
Unique features: Ovoviviparous
Fun fact Black cysts due to host melanization around parasite

Question 16

Clinostomum sp.

Answer 16

Common name: Yellow grub disease
Type: Digenean trematode
DH: Piscivorous birds
1st IH: Freshwater snails: mainly Lymnaeidae (Lymnaea stagnalis, Pseudosuccinea columella), sometimes Planorbidae
2nd IH: Fish — skin, fins, and muscle tissues
Site: Black cysts on the skin
Unique features: Ovoviviparous
Fun fact Black cysts due to host melanization around parasite

Question 17

Argulus spp.

Answer 17

Common name: Fish louse
Type: Crustecean, Brachirua of freshwater, brackish and marine fish
Site: Generally live on the external surfaces of the skin and fins. They pierce the external tissues of the host and ingest cellular fluids that can lead to a localized reaction. Vectors of important disease.
Unique features: 3-5 mm, grossly visible dorsoventrally flattened, oval parasites have 2 prominent sucking disks, 2 dark colored eyespots and a centrally located piercing stylet