Fluorocarbon lines have been used in salt water for years but are becoming more popular in fresh water. These lines disappear underwater and become invisible to fish. They're very useful when fish are line-shy and you don't want to spook them.
The Qualities of Fluorocarbon Lines
Lines made of 100 percent fluorocarbon are the most invisible lines but they have other qualities that make them less useful. They're stiffer and less manageable on reels so they don't cast as well as other lines. And they are not as strong as other lines of the same diameter, but are still very tough and resist abrasion well. They're slick so they don't hold knots as well as some lines. They have a relatively large diameter and low stretch.
Applications for Fluorocarbon Lines
Use fluorocarbon lines in extremely clear water where you need a line that is completely invisible to the fish or whenever you go after line-shy fish. For flats fish like bonefish in salt water, invisible line can make the difference between catching fish and getting casting practice.
These lines also make good leaders for bait rigs and Carolina rigs (see Chapter 9 for more about rigs). The short length of the leader eliminates the problem with their stiffness. You spool another line that is easier to cast on your reel but still have the advantage of an invisible line between the bait and the main line.