The Florida Keys offers some of the biggest and smartest bonefish you'll find anywhere on the planet. A 10-pounder is big in many places - but not in the Keys. Fish several pounds larger are caught with some frequency. Unfortunately, these fish have been looking at flies for years, and they are difficult to fool.
Several things may give you an edge. These fish are superwary of the impact the fly line has on the water's surface. Unless it is windy, you increase your chances with a 6- or 7-weight line. For example a 6-weight line weighs 160 grains and an 8-weight, 210 grains. Some of the top fly-fishermen believe a clear-tip line adds another advantage, and they keep their cast low so the fish don't see the line in flight.