On the seahorse.org there are warnings that one shouldn't use formalin with white residue on the bottom.
The white residue is paraformaldehyde and is considered very toxic and deadly, at least to seahorses.
I don't know if that means the formalin is no good or if one can remove the residue by filtration and use the remaining product.

I used formaldehyde when I had an airborne disease on my Discus. The last poster is correct,if there is white on the bottom do not use,it is quite deadly. When using as a dip
it worked quite well although the smell when dipping the fish was disgusting. Keep a close eye on the fish as well and use a net for the dip. Good luck and I hope it works out for you.

I believe I bought mine from Safeway Pharmacy.

On the human side they use formalin to stop sweaty feet ....

I managed to get the last bottle of formalin - 3 at big als. It hasnt seemed to help out the poor little guy yet.

Shoppers, safeway, pharmasave, coop, etc all dont carry any. Id prefer to get the 37% stuff not the 3% that Kordon makes.

Well I'll look around more today.

Thanks guys,

Try a Co Op hardware store as well. I believe that farmers use it on Grain,I got a bottle there as well. Although it was a few years ago.