Sometimes it can be difficult to know when to switch flies and try something different. You are not sure whether you need to stick with the fly or change it out because the fish are looking for something slightly different. Here is some great expert input from some of our friends and fellow Orvis-endorsed guides around the country.
As you’ll see from our experts’ answers below, there are many different ways to look at the question, and opinions vary. Brown Hobson, Brown Trout Fly Fishing (Asheville, North Carolina): If fish density is high, I know fish are actively feeding, they are seeing my fly, and my drift is good, then I will only make three or four casts before changing flies. If the stream doesn’t have many fish, I don’t know where they are sitting, if I suspect they aren’t feeding super hard, or I’m having trouble getting a good drift, then I may leave it on for along time.
Some days, the fishing just isn’t good, and the best tactic is to leave your best two flies on and fish them as hard as you can. When fish are feeding hard, I find they will often take 20 different patterns that represent the bug du jour. For example, some days it doesn’t matter what color bead you have, whether the fly has a flash back, or exactly what shade of brown the fly is. Conversely when the fish aren’t feeding hard, they can be very picky and only a Pheasant Tail with a black bead, no flash, and chartreuse wire may work. I usually change often at first while I assess what my strategy should be. If all signs point to the fish feeding strong, then I keep changing till I’m popping fish regularly. Capt. Lucas Bissett, Low Tide Fly Fishing Guide (Slidell, Louisiana): In a saltwater situation where I’m sight-fishing, I let the fish decide if or when I change. If I see multiple fish react negatively to my fly, I change. Kyle Wilkinson, Trouts Fly Fishing (Denver, Colorado): My biggest rule for when it’s time to switch flies is when you begin to lose confidence in what you have tied on. It doesn’t matter if the fly you’re fishing is working for your fishing buddies, is what the local fly shop recommended, or what you read about on a fishing report. As soon as the confidence in your fly selection begins to fade, it’s time to switch. Sometimes that may be as simple as switching from a copper Copper John to a red Copper John. One Baetis pattern for another. Switching from a size 18 to a size 20. Etc etc. It doesn’t always have to be a drastic switch. Capt. Dave Pecci, Obsession Charters (Charlotte Harbor, Florida): Assuming you are making presentations where there are fish and not just blind-casting: I usually make 6 to 10 casts of varying retrieves, and then change up. It’s also a good idea to move off the fish to let them settle down and come back 20 to 30 minutes later. They may know you are there and develop lockjaw. Tim Linehan, Linehan Outfitting Co. (Troy, Montana): Determining when to change flies does not have to seem confusing or vague. The better way to approach the subject is to ask yourself why your present fly might not be working. For the sake of simplicity, let’s assume you know you’re in productive water and that your drift is good, so that leaves us with an ineffective pattern as our only concern and how and when you might consider changing it.
- The first reason to consider changing your fly should be all about whether you want to concentrate efforts near or on the surface of the water or somewhere in the water column. The old advice regarding dry fly fishing is to match the size, silhouette, and color of the naturals provided you’re seeing rising fish and natural insects are actively hatching, laying eggs, or otherwise animated on the surface. If there is no activity near the surface, consider changing flies and trying a nymph or streamer to penetrate the water column and concentrate efforts to that end.
- The second reason to consider changing your fly involves more specific themes. If you’re still generally fishing near or on the surface, and you’re not catching fish but fish are rising and active, you have the wrong pattern. Consider changing flies frequently. It could be that you think fish are taking adults on the surface but they are really concentrating on swimming nymphs or emergers. By changing flies frequently you will increase your chances of hitting the jackpot more quickly.
- Finally, and this has always been my modus operandi, give a fly 10 minutes if you know you’re in productive water. If it doesn’t produce, change it. Be aggressive. You have all those boxes and all those patterns yoked around your neck and in your vest. Use them.

- When blind-casting for trout, try changing flies when you have covered a few prime holding spots and/or feeding lanes thoroughly with good casts and drifts.
- When sight-casting to trout, try changing fly every 2 to 3 fish if you aren’t getting any looks or takes with good presentations and drifts.
- If trout are attracted to but refusing the fly, it usually means you’re close to the right fly, so change to a smaller fly. If changing to a smaller fly doesn’t help, try dropping down a size in tippet or a similar fly tied in a different style.
- Check the leader and tippet for tangles knots, kinks, etc. that the fish may be seeing or that may be affecting the quality of the presentation.
- Analyze the quality of the presentation. For dry flies and nymphs, is the fly being presented in a drag-free manner? In the case of nymphs and streamers, does it need to be deeper? For streamers, I try changing up the retrieve for a few more casts.