Monofilament is popular as a line material because of its low memory and suppleness, which make it easy to cast and handle. Furthermore, mono boasts excellent knot strength and abrasion resistance, and has an inherent stretch that makes it forgiving when subjected to sudden strain. It's also fairly inexpensive.
But stretch can also be perceived as a disadvantage of mono, since it may reduce the sensitivity needed to detect subtle strikes, as well as limit the angler's ability to set the hook solidly in certain situations, such as when bottom fishing in deep water. Mono also absorbs water, and can lose as much as 15 percent of its rated breaking strength when saturated. Lastly, mono weakens considerably under repeated exposure to the sun's ultraviolet rays. Fluorocarbon's biggest selling point is its low visibility. This is due to its refractive index - the degree to which light bends or refracts as it passes through a substance - which can be as low as 1.42. That's very close to the refractive index of water (1.3). The refractive index of nylon monofilament is higher than that of fluorocarbon, coming in at about 1.52. Braided lines have virtually no stretching capacity. On one hand, this has the great advantage. When you are fishing at greater depths you always maintain direct contact with the bait. On the other hand, when you are fishing with the light power rods you must adjust the drag more softly than when using monofilament lines of the same breaking strength. braided lines are 3 – 4 times stronger than monofilament lines of the same diameter. They are perfect for sea and surf fishing.
Fluorocarbon also contains more material than mono, is non-porous, and has a harder finish. It's virtually a solid material that's denser than water. That means it sinks and doesn't absorb water, the latter quality enabling it to maintain its rated breaking strength whether wet or dry. Furthermore, it has a diameter that's comparable to or smaller than monofilament of the same strength, and also has very little stretch. Both features enhance fluorocarbon's sensitivity and hook-setting ability. Lastly, fluorocarbon is very abrasion-resistant and less susceptible to damage from the sun and chemicals.
On the down-side, original fluorocarbon is much stiffer than nylon monofilament and retains a fair amount of memory. That's why fluorocarbon has excelled as a leader material, but hasn't been manageable as a fishing line. Another drawback has been price, since fluorocarbon leader material costs considerably more than monofilament and braided lines.
However, all that is about to change with the arrival of new fluorocarbon fishing line. Banking on the popularity of fluorocarbon leaders, several manufacturers have recently introduced technologically advanced formulations of fluorocarbon that are slightly "softer" and more flexible than the original material. Although these new fluorocarbon products retain nearly all the advantages of the leader material, they're intended for use as a primary fishing line. They're reasonably priced, and are already becoming quite popular with salt water anglers.
Four parameters must be taken in consideration when choosing a fishing line: stretch, linear tensile strength and strength on the knot, limpness and color.
Linear tensile strength and strength on the knot
Usually line breaks at the knot. The strength of the knotted line is decreased. The reason is folding damages of the outside molecular level.
Limp line does not form stiff coils that rub the guides. A stiff line has a harder finish and is not so vulnerable when fishing in weeds or rocks that scuff the line.
Most of anglers use clear, silver or green line when fishing in clear water.