I. Copepod parasites

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I. Copepod parasites
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Argulus

• External, fish lice
• primarily a pond problem
• visible, flat, move about
• 2 sucking disks for attachment
• Pierce skin with mouthpiece and feed on blood.
• Large number vs. small number
• Secondary infections occur

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Lernea

• Slender copepods with anchor attachment (5-22mm)
• anchor causes tissue damage
• Secondary infection

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Lernea

• Easily identified
• Primarily warmwater fish
• Egg sacs are very obvious

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Ergasilus

• External
• Small (1.5 - 2.5 mm)
• Gill parasite
• Many fish species

• Only females on fish
• Claw like claspers
• 1 million eggs year
• live 1 year

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Actheres ambloplitis

• External
• Common on catfish
• Gill parasite
• Attach by leg like structures
• Egg sacs
• Especially bad on larval fish

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II. Trematode parasites
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Gyrodactylus

• External, visible
• Monogenetic (complete life cycle on fish)
• Live young - move readily
• No eye spots
• Haptor with 1 large pair of hooks and 16 hooklets
• Skin irritation but also on gills and fins
• Signs are listlessness, frayed fins, flashing,
  fungus
• Heaviest in winter and spring

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Dactylogyrus

• Monogenetic
• Lay eggs in water (not as explosive as Gyro)
• 4 eyespots
• 1 pair hooks, 16 hooklets

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Dactylogyrus

• Primarily a gill parasite
• So cause gill damage and symptoms can be mistaken
  for O2 problem or other gill infections
• Primarily warmwater, especially cyprinids

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Cleidodicus

• External, monogentic
• Eyespots
• 4 large anchor hooks
• Lay eggs
• On gills is problem
• Symptoms looks like O2 problem
• Warmwater fish, especially catfish

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Digenetic trematodes

• Quite a number are problems
• Some internal, some external
• Require more than 1 animal host
• Sanquinicola in salmonids
• blood fluke
• snails are intermediates

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Digenetic trematodes

• Various types of yellow and black grubs
• common in wild but in ponds also
• aesthetic problem only
• don't know why not in text
• snail - fish - bird cycle

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III. Protozoa
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I. multifilis

• Large ciliated protozoan
• Primarily ww fishes but some cw
• White color with large horseshoe shaped nucleus
• Flash, twitch, flag
• Heavily infested fish are lethargic
• Skin, gills, fins - penetrate skin so not exactly
  external
• Can be explosive since 1,000 or more from one
• At 70-75o life cycle only 3-4 days
• Only free swimming vulnerable

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I. multifilis
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Chilodonella

• External
• Numerous species
• Small, oval, colorless, ciliate (faint bands)
• Skin, fins, gills
• Both warm and cold but primarily warm and under
  crowded cond.
• Signs -- listless, off feed, flashing, lie on
  side
• Easy to control

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Chilodonella
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Ambiphrya

• Several species
• Small urn-shaped ciliate
• Ring of cilia at top end and band of cilia in
  middle
• Skin, gills, fins of salmonids and warm water
  fish - particularly bad on bass and catfish -
  young
• Usually harmless, but if a lot the scopola
  (attachment organism) smothers gills.
• Signs -- piping, may look like bacterial gill
  disease, redden skin gills, listless
• Easy to control at this time

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Epistylis

• Stalked ciliates
• Usually on skin but also gills
• Also eggs (fuzzy so can confuse with fungus)
• Trout, walleyes, catfish, others
• Signs
• flashing
• secondary infection

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Epistylis
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Trichodina

• External
• Ciliate - many species
• Saucer shaped, rows of cilia, especially on
  margin.
• Skin, fins, gills, activity
• Signs -- flashing, tattered appearance of fins,
  white irregular blotches
• secondary bacterial problems

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Hexamita salmonis

• Octomitus, internal
• Tiny flagellate
• Colorless (must stain), pearshaped - 8 flagella
• Salmon and trout intestines
• Irritate gut lining, irregular swimming, yellow
  intestinal fluid
• Some question its status as a pathogen.
• Apparently more of a problem when non-prepared
  foods fed

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Ichtyobodo

• Costia, external
• Flagellate, small, pearshaped, flickering flame
• A couple species
• Trout, salmon, ww fish especially bad on trout
  fingerlings and catfish

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Ichtyobodo

• Signs
• light bluish - grayish film
• lose appetite
• flash
• crowd bottom - listless
• have to examine microscopically

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Henneguya

• Internal
• From many species warm and cold water
• A myxosporidean
• Encysts in tissue
• Muscle damage, but some stages on gills so
• No control

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Ceratomyxa shasta

• Internal myxosporidian
• Salmonids
• Has caused many epizootics of 100 mortality
• Intestine and gall bladder, spleen, liver, and
  kidney
• Signs
• vent area swelling
• distended abdomen
• early are listless, off food, seek slack water
• fish may darken
• No treatment - transmission method unknown

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Myxosoma cerebralis

• Internal myxosporidian protozoan
• Twisted spines and deformed backs
• Salmonids
• Whirling or tail chasing is a sign "called
  whirling disease"
• Survivors often deformed and have "Blacktail"
  (loss of chromatophore control)
• No known control method except prevention
• Really a problem in young fish

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Plistophora

• Internal
• Several species
• Small (3-6 microns) beanshaped
• Trout gills, golden shiner ovaries (reduces
  fecundity)
• No control

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Plistophora
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Cryptobia borreli

• Flagellate
• Variety of fishes including salmonids
• A blood parasite, affects kidney function
• Signs
• anemic
• popeye (exophthalmic)
• fluid in body cavity
• No treatment

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IV. Fungal disease
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Fungal disease

• Pervasive
• Numerous species including Saprolegnia
• Fish and eggs
• Warm, cool, cold
• Appears as a white cottony growth on eggs on fish
  is white to brownish patches on various body
  areas
• Any damage to body surface can open way,
  spawning, netting, handling
• Control by sanitation, or chemicals, for others
  no control
• Often prophylactic type treatment of eggs

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Saprolegnia
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V. Bacterial disease
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Furunculosis

• Aeromonas salmonicida -- Salmonids
• Cause muscle lesions
• Can enter through scratch or digestive tract
• Bacteria produces a toxin
• Signs
• blisters or patches - bluish - red or purple
• hemorrhages at fin bases or frayed dorsal fins
• acute lesions
• Short incubation

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Furunculosis
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Pseudomonus

• Also called fin rot
• Signs
• superficial grayish - red skin ulcers
• dropsy
• popeye
• inflamed fins
• Many fishes affected - frogs also
• Much different than fin rot
• Warm and cold
• Variety of symptoms

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Cytophaga psychrophilia

• external
• Usually called peduncle disease
• A low water temp. disease
• Signs
• darkening
• lesions on peduncle or near pectoral fins
• Worst on young fish
• Can result in total erosion of caudal area
• Primarily a problem in 40-50oF range

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Yersinia rucheri

• Causes enteric redmouth disease in salmonids
• Inflammation and erosion of jaws and palate
• May kill more RBT than any other bacterial agent
• Signs
• black, popeye
• lethargic, drift at surface
• mouth and tongue inflamed, underbelly with spotty
  hemorrhages
• dead fish with dropsy
• fin sockets hemorrhaged, in heavily infected fish
  - gill bleeding
• Especially a problem in intermountain west and
  still growing
• Worst in hot summer months

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Bacterial Gill Disease

• external
• Called GD often
• Salmonids and warm water (but primarily salmonid)
• Superficial infection of gill epithelium
• By an undecided bacteria, probably related to
  columnaris disease causative agent

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Bacterial Gill Disease

• Above 56o becomes more of a problem
• Fish can't get rid of CO2 and ammonia or get O2
• Often secondary fungal infection
• Signs
• lethargic, off food, pipe, "ride high"
• whitened gill tips, excess mucous
• Worse in fingerlings

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Flexibacter columnaris

• external and internal
• Columnaris disease
• Through skin and gills, especially if scratched
• Seldom a problem below 55oF worse at 65oF
• Primarily salmonids and catfish
• Signs
• grayish white body lesions with bright yellow
  slime
• common on head and mouth
• internal also

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Hemophilus piscium

• internal
• Ulcer disease
• Ulcers or sores on surface of fish and work
  inward
• Resembles furunculosis but opposite sores work in
  but in furunculosis work out
• Circular sores
• Salmonids primarily

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Tuberculosis

• Related to human tuberculosis bacterium
• Salmonids
• Almost no problem now since don't feed fish
  viscera products
• External and internal lesions
• kidney, spleen, liver, digestive tract

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Tuberculosis
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Vibrio anguillarum

• internal
• Called Vibriosis
• Many fish
• Primarily a problem of marine cultured fish
• Signs
• off feed
• lethargic
• erratic swimming, spinning
• bloody discharge from vent
• internal

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Renibacterium salmoninarium

• internal
• Causes kidney disease
• Salmonid problem
• Kidney lesions but can develop into musculature
  fluid in body cavity, dropsy
• Really a lot not known about this and is a real
  problem

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VI. Viral diseases
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Infectious Pancreatic Necrosis (IPN)

• Salmonids, NA Europe
• High fingerling loss
• Over 6 in. are carriers
• Signs
• death rate up for healthy looking fish in fact
  some of best looking die first
• some spiral and roll
• tail chasing, darkening, popeye, dropsy
• internal also
• A small pathogen
• June and July worst months

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Viral Hemorrhagic Septicemia

• Primarily Rainbow Trout
• Not bad on fry or adults - middles ones worse
• Not egg transmissible but
• Signs
• color, popeye
• hemorrhage at fin bases
• lethargic, seek edges
• internal also
• Late winter, early spring

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Infectious Hemapoietic Necrosis (IHN)

• Rainbows and some other salmonids
• Not egg transmissible but a lot not known
• Ovarian fluid can do it
• Signs
• flagging
• dark, lethargic, popeye
• hemorrhaging tissue near vent and fins
• pale gills
• internal also
• April to June

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Channel Catfish Viral Disease

• CCVD, CCV
• Signs
• when temperature reaches 70oF sudden increase in
  death
• spiralling or swimming abnormally
• convulsions
• just before death at surface with tail down
• fin base hemorrhage
• internal also
• Often obscured by columnaris
• Appears to be host specific for catfish

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Lymphocystis

• Many fish but walleyes and centrarchids worse
• Mostly aesthetic, chronic
• Abnormal growth of connective tissue - wart like

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Lymphocystis