Parasitism in Freshwater Fish

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Parasitism in Freshwater Fish

• Jonathan King

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Numerous types of parasites

• Protozoans
• Trematodes
• Nematodes
• Cestodes
• Crustaceans
• Leeches

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Protozoa

• Ciliates
• Large protozoa up to 2mm in length that have
  cilia (hair like organelles) covering their body
  at some point, if not all, of their life cycle
• Flagellates
• Protozoa equipped with one or more whip-like
  flagella used for propulsion

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Ciliates

• Largest group of protozoa
• Direct life cycle
• Common in pond-reared fish
• Easy to eliminate in aquarium due to controlled
  conditions
• Easily transmittednets, hoses or hands

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Ciliates cont.

• Symptoms include
• Skin or gill irritation
• Rubbing and abnormal breathing
• Species
• Ichthyophthirius multifiliis
• Tetrahymena
• Apiosoma
• Epistylis

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Ichthyophthirius multifiliis

• Disease
• Ich or white spot disease
• Responsible for majority of fish fatalities
• Symptoms
• Small lesions on body or fins
• If gills onlyno lesions but a thick mucus
• Size
• 1000um diameter

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Ichthyophthirius multifiliis cont.

• Identification
• Horseshoe shaped macronucleus
• Possible mis-ID
• Immature forms may resemble Tetrahymena

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Ichthyophthirius multifiliis
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Ichthyophthirius multifiliis cont.

• Life cycle
• Theronts infect fish t0
• Dig under scales or gills
• Mature trophozoites leave fish t7days
• Settle and secrete cyst
• Cysts rapidly divides to produce hundreds of
  tomites
• At maturity they leave cysts looking for host
• Whole cycle 10 days to 4 weeks (temp)

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Ich Treatment

• Life cycle is temp dependent
• So raising the temp increases life cycle to days
  instead of weeks
• Formalin
• Chelated copper
• Copper sulfate
• Treat for gt3days after last spot gone

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Any last thoughts on Ich

• Well you can vaccum the floor of tank to get the
  cysts?...not extremely effective but buys time
• If diagnosed early
• Treatments may be effective
• If infestation in advanced stages
• Fish may be immune
• Toilet

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Tetrahymena

• Donde esta tetrahymena?
• Living in organic debris
• Body surface of your favorite fish
• Treatment
• Same as Ich
• If internal like the eyes
• toilet

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Tetrahymena
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Apiosoma

• Location
• Gills, skin, or fins
• What does he look like?
• Vase like
• Oral cilia
• Treatment
• Very treatableformaline, copper sulfate..etc

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Apiosoma
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Epistylis

• Stalked ciliate very similar to apiosoma
• Danger
• Greater concern than most due to proteolytic
  enzymes secreted by the organism
• The enzyme breaks down proteins in the skin of
  the fish making the fish susceptible to bacterial
  infection

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Epistylis

• Treatment
• Salt
• .02 salt solution for extended period
• 3 salt dip
• More than one treatment required

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Flagellates

• External and internal
• High magnification
• 200-400x
• species
• Spironucleus
• Ichthyobodo
• Myxozoa
• Microsporidia

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Spironucleus

• Location
• Intestinal tract
• Symptoms
• Extreme weight loss
• Distended abdomen
• Yellow mucoid build up in intestines

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Spironucleus

• Diagnosis
• Intestinal prep _at_ 200-400x
• High countstoo many to miss
• Treatment
• Metronidazole bath
• 5mg/L
• Every other dayone week

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Ichthyobodo

• External Flagellate
• Large amounts of mucus
• Blue slime disease in catfish
• Location
• Gills, skin and fins
• Diagnosis
• Microscopic examination.
• Treatmentformalin, copper sulfate..etc

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Myxozoa

• Widespread in native or pond reared fish
• How bad is it?
• Most infections not bad
• But some may be seriousyoung fish

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Myxozoa

• Extremely abundant and diverse
• Speciation
• Based on spore shape and size
• Examination technique
• Preps of infected area
• Histologic sections of tissue

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Myxozoa cont

• Symptoms
• Vary depending on the organ affected
• Excess mucus productions
• White or yellowish noduleson target organs
• Diseases
• Whirling disease- salmon
• Wasting disease

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Myxozoa

• Treatment
• Toilet
• No remedies known
• Spores can survive gt1year
• Disinfection necessary after removal of infected
  fish

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Microsporidia

• Intracellular parasites
• Require host tissue for reproduction
• Mode of transmission
• Ingesting spores from infected fish or food
• Symptoms
• Small tumors in various tissues
• Enlargement of hosts cells cause tumor like masses

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Microsporidia

• Clinical signs
• Dependent on tissue infected
• from no lesions to dead
• Serious casescysts enlarge to a point that
  organs no longer function correctly

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Microsporidia

• Infections caused
• Pleistophora
• Infects skeletal muscle
• Cysts?
• Treatments
• None available
• Spores tough
• Can survive long periods
• Most environmental conditions it can handle

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Microsporidia

• So what am I supposed to do?
• Flushing of infected fish
• Disinfect the environment

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Conclusion

• Poor water quality, crowding, stress and diet
  issues are main issues with fish susceptibility
  to parasitism
• So if you have concerns on water quality
  issuesprevent it.

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References

• "Ichthyophthirius multifiliis." Wikipedia, The
  Free Encyclopedia. 15 Nov 2007, 0417 UTC.
  Wikimedia Foundation, Inc. 15 Nov 2007
  lthttp//en.wikipedia.org/w/index.php?titleIchthyo
  phthirius_multifiliisoldid171595742gt.
• edis.ifas.ufl.edu
• www.microscope-microscope.org
• www.aquaticparadise.com
• www.uoguelph.ca .
• www.koisite.be
• www.ars.usda.gov
• http//edis.ifas.ufl.edu/pdffiles/FA/FA04100.pdf