Many species have teeth to hold, kill or chop their prey and others have dental plates in their mouth and gullet for crushing crustaceans and mollusks. Sharks, barracuda and bluefish, for example, have teeth. Fish like red fish, bonefish and permit, have crushers. The striped bass has patches of microscopic teeth. Crushers and teeth patches work more slowly than teeth but can abrade through mono.
Once you deal with these threats to your leader, you might also have to deal with mangrove, docks, coral, rocks or other habitat during a fight. At the end of the fight, heavy mono tippet, long enough to grab helps hold a fish alongside for unhooking without break-off.
Different species of fish are more cautious of leaders than others. So for some, you must use the thinnest tippet that won’t fail and longest leader you can cast. For example, a multi-piece bonefish leader averaging from 9-12’ long, terminating with #12- #15 tippet material. And for less wary fish or in poor underwater visibility, you can stay short and thick and not loose strikes. Examples of this might be fishing for night Snook or school Bluefin tuna; using a 5’ long one-piece leader made of straight 50 lb. test.
The three materials most commonly used in leaders and shockers are clear monofilament, in nylon or fluorocarbon and metallic trace, made of stainless steel or sometimes titanium wire. I love fluorocarbon as a leader material whenever fish can’t cut or wear through it. It is much more abrasion resistant and stronger in a given diameter than nylon. I tie my leaders in advance and attach them to my flies so I’m not always cutting down the tippet or shocker to change flies. I also keep six of each leader in a leader wallet, just in case. I recommend attaching flies with Lefty's Loop Knot when using monofiament tippet and shockers.
I’ve simplified saltwater leader designs by making three groups. There are variations but these are primary. First, is the all mono tapered leader with no bite tippet for fish up to about 15 lbs. I nail-knot a foot of fluorocarbon to my fly-lines that’s 2/3 the diameter of the line end and finish with a perfection loop big enough to pass a fly through. I tie a Bimini-twist in the top section of my leader with about a six-inch loop, then double it, twist it a few times and tie a Surgeon’s Loop knot. The Bimini I like ends with a whip-finish instead of the traditional bumpy double overhand knots. The resulting four-stranded Surgeon’s loop is big enough to pass a fly through. The leader is connected to the fly-line joining the Surgeon’s loop and the perfection loop with a handshake loop. In this manner, the lighter section is joined to the heavier butt with nearly a 100% strength connection. The tapered sections of the leader are connected with blood-knots or double nail-knots if they are of greatly varying diameters.
Second, is my standard three-piece leader (see drawing) with a handshake loop for convenience and either a mono or stainless bite shocker; for fish to around 50 lbs. In certain types of sinking lines with a hard finish, I’ll tie a loop in the end of the fly-line with a couple mono nail knots for connecting the leader. If I use steel, it’s solid stainless with a loop for attachment and I’ll use a haywire to attach it to the fly. I pre-twist my loops on a wire twister I’ve had for thirty years for making muskie leaders. I also carry a Du-Bro wire straightener to remove kinks from battles.
Thirdly, for the largest fish, the leaders have three sections but the line-leader connections are nail-knotted directly, without loops, or sleeved with 50 lb. Dacron and served. When the fly-lines have 50 or 80 lb. test cores, it’s nice to have a 16 or 20 lb. class tippet that will break if something goes wrong. You can see tutorials on this sleeve and serve technique online for big-game trolling. I’ve had handshake loops break on big fish when they get slack and get out of position and then snap tight. The heavy shock tippet is joined with a double nail-knot or Huffnagle knot.
I nail-knot a loop in the end of all my fly-lines. For saltwater sizes, I connect this to the backing with a handshake loop. The loop in the backing is a four strand Bimini-twist formed by first tying one Bimini with a long single loop, then doubling it and tying the second one; ending in a short four strand loop. The Biminis are also ended with a whip-finish. I coat the knots with Pliobond. This sounds bulky but it has the highest strength and goes through the guides like a bullet.
I know all this works from learning from a myriad of guides and pulling on hundreds of fish. I also learned a lot from Larry Dahlberg when he caught and released potential world record fish and released them while I filmed. Back then when my eyes were sharp without readers, he’d occasionally ask me to rig his rods. My knots held. Next Tuesday. I’ll hopefully share something about fighting big fish on a fly rod.