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Parasitism in Freshwater Fish

Parasitism in Freshwater Fish. Jonathan King. Numerous types of parasites. Protozoans Trematodes Nematodes Cestodes Crustaceans Leeches. Protozoa. Ciliates

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Parasitism in Freshwater Fish

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  1. Parasitism in Freshwater Fish Jonathan King

  2. Numerous types of parasites • Protozoans • Trematodes • Nematodes • Cestodes • Crustaceans • Leeches

  3. 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

  4. Ciliates • Largest group of protozoa • Direct life cycle • Common in pond-reared fish • Easy to eliminate in aquarium due to controlled conditions • Easily transmitted…nets, hoses or hands

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

  6. Ichthyophthirius multifiliis • Disease • Ich or white spot disease • Responsible for majority of fish fatalities • Symptoms • Small lesions on body or fins • If gills only…no lesions but a thick mucus • Size • 1000um diameter

  7. Ichthyophthirius multifiliis cont. • Identification • Horseshoe shaped macronucleus • Possible mis-ID • Immature forms may resemble Tetrahymena

  8. Ichthyophthirius multifiliis

  9. Ichthyophthirius multifiliis cont. • Life cycle • Theronts infect fish t=0 • Dig under scales or gills • Mature trophozoites leave fish t=~7days • 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)

  10. 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 >3days after last spot gone

  11. 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

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

  13. Tetrahymena

  14. Apiosoma • Location • Gills, skin, or fins • What does he look like? • Vase like • Oral cilia • Treatment • Very treatable…formaline, copper sulfate..etc

  15. Apiosoma

  16. 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

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

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

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

  20. Spironucleus • Diagnosis • Intestinal prep @ 200-400x • High counts…too many to miss • Treatment • Metronidazole bath • 5mg/L • Every other day…one week

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

  22. Myxozoa • Widespread in native or pond reared fish • How bad is it? • Most infections not bad • But some may be serious…young fish

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

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

  25. Myxozoa • Treatment • Toilet • No remedies known • Spores can survive >1year • Disinfection necessary after removal of infected fish

  26. 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

  27. Microsporidia • Clinical signs • Dependent on tissue infected • {from no lesions to dead} • Serious cases…cysts enlarge to a point that organs no longer function correctly

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

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

  30. 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 issues…prevent it.

  31. References • "Ichthyophthirius multifiliis." Wikipedia, The Free Encyclopedia. 15 Nov 2007, 04:17 UTC. Wikimedia Foundation, Inc. 15 Nov 2007 <http://en.wikipedia.org/w/index.php?title=Ichthyophthirius_multifiliis&oldid=171595742>. • 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

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