Quote Originally Posted by WadeK View Post
There used to be a floatant that had, I think, Naptha(Dad called it Napa?) as a chief ingrediant. It floated flys great, but killed fish by coating there gills. You could also start a fire with it.
You might be referring to Ray Bergman's home made fly floatant which was naphtha (white gas) plus paraffin. You dipped the fly into the solution and the naphtha evaporated leaving a coating of paraffin wax on the fly.

http://www.drlogik.com/scans/bergman_formula.pdf

It didn't kill any fish. Floatants are hydrophobic which mean they repel water, and therefore, they cannot mix with water to coat the gills of fish. Most floatants are hydrocarbon or silicone based which are less dense than water and they float on the water. That is the sheen that is sometimes seen around a floating fly.