Do pond fish medications work in water temps below 36 degrees?

Question

I've determined the fish have ick.

Answer 1

Well, yes, it will work, but it will take a lot longer. The ich lifecycle has 4 stages and ich is only killable in one of those stages. At 36F, I would expect the ich lifecycle to very, very slow, almost halted, however it must not be if you are observing the white cysts on the fish caused by the burrowing trophonts.
At 80F, the Ich lifecycle takes about 4 days to be complete. At 36F, it would take much longer, so I suggest you use AQUARIUM SALT, not ich meds, to treat ich. Ich meds may well kill your fish, too!
Use 1tbsp per 5 gallons will do, be sure to dissolve it first in dechlor water.

Keep this salinity level for several weeks.

Answer 2

If you can bring the water temp up to at least 55 or so (maybe with a heater??), I think it will certainly work a lot better. At 36 degrees, I'd expect the entire pond to be effectively in a state of hibernation, and I wouldn't think the medication would have any effect at all.

Answer 3

This in my pond experience would be extremely rare! You may have other problems or bacterial nodes growing on your fish.
What are your water parameters?
Most ich medications are much more effective and safer at a pH
above 7.2 and a kH of 80 ppm or more.
What is your water circulation like? If you have poor circulation and little dissolved oxygen (oxygen is exchanged at the surface), many times the Redox will be low and nodes that mimic ich will form.
If you do have poor circulation, poor dissolved oxygen levels, low kH (which will all result in a poor Redox Potential), first improve this before ANY therapy.
Be careful with salt with lilies and other pond plants.
Pimafix is relatively safe here for bacterial infections while Quick Cure (malachite/ formalin) is relatively safe at the proper pH and kH.

For more pond information, please visit this URL:
http://www.americanaquariumproducts.com/ClearPond.html

For more ich information:
http://www.americanaquariumproducts.com/Aquarium_Ich.html

Answer 4

Great resource:

http://www.fishlore.com/Forum/freshwater-fish-disease/ick.0.html
http://www.aquatic-oasis.com/articles.htm

I have not had that problem with mine but I think below 50 degrees the pond is pretty much in hibernation and so it may not work but read the resources.