Some fly anglers simply don't realize how much of an impact the wrong size fly line or leader can have on their fishing. In the most touchy, technical conditions, it can literally be the only thing that's hampering success. I've always loved fishing with tackle that's on the lighter side for two main reasons: it's more fun, and in many cases it most definitely helps me catch more fish. Here's just some of the reasons you might consider downsizing your line the next time you hit the water.....
Why Fish With a Lighter Fly Line?
Delicacy- The same make/style fly line but in a lower line size will land more gently due to less weight and thinner diameter. Remember, simply dropping down line size might not matter so much if the line you're switching to has a different design, such as a shorter, more aggressive taper. Keep in mind also that different lines of the same line weight can have different grain weights, too. One WF6F line might be spot on to AFFTA standards at 160-grains, while another type of WF6F line from the same or a different company might check in at 185-grains. It really pays to look beyond just the line size listed on the box.
Easy/Fun- Lighter fly lines and their corresponding lighter fly rods are easier to cast provided the wind isn't a problem. This means less effort, fatigue, and more fun both casting and fighting fish! I can immediately think of places I fished a 7-weight in the past where I now often prefer a 5 or 6 both for the increased ease, enjoyment, and seemingly higher success rates. Even if you're throwing weighted or bulky flies, a lighter fast-action rod can be surprisingly capable matched up to the right line.
Saves Money- How can a lighter setup save you money? One way is because lighter rods used to throw these lighter lines can sometimes be priced slightly less than rods of heavier line weights, even if they are in the exact same series. Secondly, maybe you can avoid buying that extra rod that you thought you needed? Perhaps the one you already own will work for more than you think.
Let's say you have a 6-weight rod you fish streamers with for trout. You're thinking about getting into largemouth bass fishing on some of the local lakes, but the two articles you read recommend 7–9 weight rods for chasing bass. That might be true for some places, but a 6-weight can be a stellar bass rod (and can throw decently-sized flies) so long as you're not fishing around thick cover or throwing very large bass bugs. I speak from experience here!
Why Use a Lighter Tippet?
Fish Deeper- A lighter tippet can allow you to fish deeper. As line gets thinner, this means less resistance and a faster sink rate. Keep in mind that line diameters can vary between manufacturers. Fishing a good thin fluorocarbon can be even better for getting deep since fluoro sinks faster than average monofilament due to its density.
Less Visibility- The lighter, thinner line will be less visible and is less likely to be seen by fish. In calm, clear waters this can make a huge difference. Again, using a thin fluorocarbon can provide a real double-whammy because fluorocarbon is already less visible underwater than comparable mono.
Better Fly Action- The lighter the line, the more natural a fly can swim or drift. When it comes to nymphs and dry flies, using a thin, supple tippet lets the current move them around fluidly. This is important for maintaining that natural, drag-free drift. Streamers benefit as well with better sink rate and more freedom of movement whether swinging or stripping.
Everyone's fishing situation is different, and tackle should never be so light that you have to fight the fish for an abnormally long length of time. Fighting a fish in this way can put undue stress on them and have a bad end result. You must also take things like cover, structure, fish size, and current into consideration. Going light can increase your success as a fly angler, but do so within reason!