Anythingfish Home     Gill Fluke Infestation, Gyrodactylus, in Redtail Catfish      Ted's Master Index

December 20, 2004



Gill flukes - found in many Koi ponds and nearly all fresh-water lakes and streams - cling to fish gills and skin.  While small numbers may not be a problem, when conditions are optimal (for the gill flukes) they multiply very rapidly.  Infected fish begin flashing (rubbing on the bottom), become lethargic and die; the weakest ones first. 


When should you suspect gill flukes?  When some or all of your pets are behaving out of character, not feeding, rubbing on the tank sides and bottom or remaining motionless, suspect and investigate a potential problem.  But is it flukes or another fish health issue?  Look at fish tissue scrapings under a microscope.  If you see flukes then you know and may begin treatment immediately; if not, then you know what it isn’t.


My favorite high-energy, 10 year-old 30” Amazon Redtail Catfish stopped eating and appeared lethargic.  Before I realized what was happening I was shocked by its sudden death.  I did not suspect gill flukes.   Dr. Roger Hancock, DVM, Pilchuck Veterinary Clinic in Snohomish Washington, suggested I pack the fish in ice and ship it to Washington State University in Pullman for an autopsy.  The College of Veterinary Medicine phoned me with their findings the following day, but since I had not begun treatment for gill flukes quickly enough, I lost a second Redtail Catfish.


The water in the 2400 gallon tank (containing the Redtail Catfish and other fish), had a very high Nitrate NOł level, over 400 PPM.  Redtail Catfish are more susceptible to poor water conditions than their tank mates. 


TREATMENT:  I immediately drained 2,000 gallons, then very slowly refilled the tank over the next 16 hours, maintaining the 75° water temperature.  Next I added 75 pounds of salt, bringing the water to a .3% level, 3 pounds per 100 gallons.  The salt was added to help prevent secondary infection and improve the slime coat of the fishes.  Finally I treated the tank with Argent Chemical’s Trichloracide gill fluke treatment. 


Several days later a third Redtail Catfish died.  Again I drained 80% of the water and refilled the tank, added salt and Trichloracide.  No more fish died and all three remaining Redtail Catfish are looking very good and eating well.


I would appreciate hearing from anyone who has had similar Redtail Catfish problems or can shed more light on this event. 


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