Q: What are your thoughts on fluorocarbon versus monofilament? I can't seem to make up my mind if or when I should use one or the other.
A: I have mixed feelings on this subject too, Harry. I believe there are situations where fluorocarbon is best, but most of the time I prefer nylon.
If a fish has large eyes (good eyesight) and feeds in clear, open water (such as tuna and giant tarpon), fluorocarbon may produce more strikes. However, permit and bonefish also have large eyes, but since they feed on the bottom, properly presented flies and leaders should similarly be in close proximity to the bottom. In cases like these, I prefer mono.
Fluorocarbon has vastly improved over the years, and the material differs by manufacturer. Much has been made about fluoro sinking faster than mono, but when they are attached to weighted flies, this is a moot point.
For most situations, I prefer premium nylon to fluorocarbon. Nylon is less expensive, more flexible and tends to knot better. I generally use fluorocarbon as a tippet material.