the formalin should be good. i doubt you'll be able to find this, but the old doc wellfish has a product that they made in capsule for called "general cure". i've used it before and it worked great. but you're increasing wc's and raised heat, so things should be looking better. good luck bud.According to this article, popeye can be caused by parasites as well, which would explain resistance to broad spectrum gram negative antibiotics. I am now treating with malachite green and formalin. We'll see how it goes. The good news is it says that this disease is rarely fatal.
http://www.fishpalace.org/danscomments.html#Popeye
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