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Category: Pet
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Something is killing off my large goldfish & koi in my pond.

Customer Question

Something is killing off my large goldfish & koi in my pond. they seem to have a white slime over the body. Not ick nor looks like any fungus I have ever seen. Have been having a bad algae problem but this has just happend and is killing fish off quickly just over a couple of days. The pond is a large cement pond that has been established for 30 years. Only other fish kill was a couple of years ago when a Great Blue Heron made short work of very large koi and gold fish that had been in the pond for 30 years!
Submitted: 6 years ago.
Category: Pet
Expert:  TROPICAL FISH AFICIONADO replied 6 years ago.

Your fish are dying from a bacterial disease called Slime Disease and/or a parasitic infection which mimics the symptoms of Slime Disease.


What I recommend be done to treat this is start off by changing 20% of the water in the pond. Then add pond salt to the water at a ratio of 1 lb per every 80 gallons of water. This is a particularily high dose that will eliminate parasites but not harm the fish.


Once the above has been done begin to treat with a medicine called TetraPond Pond Fish Treatment which is a wide spectrum medicine. Click on link below for a view and description of the product which is sold at most major pet stores and online. Once adding the initial treatment leave it in the water as is with the salt. After one week has passed add another dosage. Before adding the second dosage do another 20% partial water change. Do not add any salt when doing the second water change.


The combination of the partial water changes, addition of salt and the use of the TetraPond treatment should fix the problem in your pond.


Best wishes.





TROPICAL FISH AFICIONADO and 3 other Pet Specialists are ready to help you
Customer: replied 6 years ago.
My pond is 55,000 with live plants in very large pots. Will treating with that much salt kill my plants.? I guess I'll have to order the Tetra Pond on line as I doubt I can get that quanity locally
Expert:  TROPICAL FISH AFICIONADO replied 6 years ago.

Yes the salt might harm or even kill some of the plants but it basically comes down to the plants surviving or giving the fish a chance to survive.


Thank you for your accept and bonus and please let me know if you have any questions.



Customer: replied 6 years ago.
i can only find tetra Pond Pond Fish Treatment in 16oz bottles will take 22 bottles Any thing else I might use that I can use now because by the time I can get that quanity excpt online which will take to long to get here to do any good. I can get the salt????? What can I do?
Expert:  TROPICAL FISH AFICIONADO replied 6 years ago.

Hi again and sorry for my delay in getting back to you.


I can certainly understand your predicament having a pond of this size so instead of using the TetraPond Treatment use a medicine called Potassium Permanganate which is found at some pet stores, hardware stores and online. Click on link below for an overview of the medicine.


If you decide to use this medicine you'll be able to save on the expense of using/adding pond salt as it won't be necessary.


Be very careful when doing Potassium Permanganate as it's potent stuff. Make sure to carefully follow the directions on the product label before dosing.





Customer: replied 6 years ago.
Expert:  TROPICAL FISH AFICIONADO replied 6 years ago.
You're most welcome!