" When Should I Change Flies? "
There are certain questions that nearly always come up when teaching a group of new fly fishers. At our fly-fishing schools Lynda and I nearly always hear “Does everyone get tangled this often?” and “Do I really need a tapered leader?” but the big one is,
“How do I know when to change flies?”
It sounds like a pretty straightforward question, but there’s more to it than is apparent initially. You should change flies when you know that the fish isn’t going to take the one you’re using now. Assuming that you haven’t frightened the fish while casting to it, once you’ve shown a fish a fly that is behaving properly (ie, without drag if it’s a dry or a nymph) three or four times without acceptance, it’s time to change. But it doesn’t necessarily mean change the fly; it means change something.
The worst thing is to continue indefinitely with something that’s not working.
So changing the fly is only one of the things you can change. Another is the method. If the fish won’t take a dry fly, try a nymph or streamer.
Another possibility is a change in your casting position. If you’re not absolutely sure that your fly is drifting over the fish without drag, consider whether a step or two one direction or another will place you in a more advantageous casting position. Or, if the water is slow, flat and clear, you can try delivering your dry fly from a position upstream and across from the fish using a reach cast. If you do this the fish will see the fly before it sees the leader, and if leader-shyness is a possible reason the fish is rejecting your fly, this might solve it.
Along with possibly changing the fly, the method or your position, you can opt to completely change your location. Simply choose another place to fish - a different spot on the stream or the lake or maybe a different body of water altogether.
Which change you make depends somewhat on your personality and mood. If you’re determined to fish dry flies, try a couple of different ones in a good spot, and if that doesn’t work keep fishing dry, but in different places in the lake or stream. On the other hand, if you’re determined to catch a fish in a particular spot that you believe holds fish, stay there, but try different things to see if you can figure out what the trout want.