i know nothing about the type of fish u have and medication. but i used copper sulphate. mardel coppersafe actually. im still treating the tank but my fish was eating again with no signs of velvet in 3 days. salt and temp raise works good on ich but i had absolutely no affect with that treatment on velvet. i tried salt and heat for over a week. the box says can be harmful to some snails and invertebrates but thats it.