You can catch mahseer by swinging flies, stripping streamers, dead drifting sub-surface patterns, or skating big dry flies on top. You can even catch them with hard-bodied poppers, lures and spoons, yes, spin fishing and bait casting.
The most enjoyable, however, must be sight fly-fishing for the mahseer with big dry terrestrial flies such as hoppers.
The ability to sight a fish before casting to it gives you an edge. Spotting that fish first gives you the time and information needed to come up with a methodical and effective approach.
What cast do you need to make and where do you need to make it from?
Is it looking up or is it swinging for nymphs? How deep is he?
It also gives you the information you need to make the necessary adjustments such as if the fish refuses your fly you can see that.
Maybe there is too much drag, or maybe it’s the fly itself.
It also gives you the opportunity to target individual fish. Smaller, less desirable fish will always lunge at your offerings with gusto. There is almost always more smaller fish than big ones.
Either way, if you can put the fly accurately to where the fish are you will catch more fish. Plop, and all it takes is one or maybe two seconds before your fly disappears in a splash!