Anglers complaining about slow, even tough, fishing last week on waters that fished well previously should have nothing to complain about this week.

The full moon is waning and each day it’s past full, fishing will become better for longer periods in lakes and rivers.

To prove daytime fishing gets better as the moon wanes, a Bozeman angler visiting the Cody area this weekend hooked and landed a 24-inch brown trout with a massive girth on a grasshopper fly pattern on a river he requested go unnamed. I can’t say I blame him for the request, but this river is not a secret for those who know early October can put some large brown trout in the net on the lower Clarks Fork of the Yellowstone. This is especially true on full moons that occur in late September and October.

He said he had caught several nice rainbows and thought they were huge, then his next cast with his fly raised this really massive head out of the water. Once the fly disappeared as the trout turned to go back to the deeper water, he set the hook, thinking he had caught a cutthroat due to the fish’s color. It wasn’t until he had brought the fish close to the net that he realized his catch was a brown that went past huge and entered the boss hog, or monster, category.

The brown, a female, was kept in the water (even for a quick snapshot in the net) the entire time before being released healthy and alive. Kudos to the angler. She was probably on her way to her fall spawning area when the angler happened to be standing in the right place at the right time with the right fly for what might be a once-in-a-lifetime accomplishment.

Despite the Bozeman fly fisherman’s success, hopper action isn’t like it was in September. October is the month cool weather slows down hopper activity to be replaced by midges, mayflies and fall caddis flies. Hoppers still work well, especially on really sunny, warm days with a stiff breeze, which makes rubber-legged and foam-bodied hopper flies move and act weird, something no respectable predator can resist attacking when it knows the cold winter months are not that far away. But the trout just act like they have had enough steak for dinner and prefer to graze leisurely.

This means the trout seem to want something different and more variety. Smaller aquatic insects, especially like blue wing olives, midges and caddis are the snacks on the surface, while aquatic sowbugs, scud, aquatic worms and leaches dominate a trout’s rumination. Larger trout will get the random Big Mac attack and, again, smack a hopper pattern, but more often they key in on streamer flies that look like smaller trout or baitfish. The latter has a random feeding pattern, but nothing to ignore should you find the trout acting fussy during or just after a full moon phase in the fall.

If you find the fish picky but willing to eat occasionally, but not consistently on one fly, don’t stick with what worked a week ago. This is October. Switch your thinking by correctly using size 14 and smaller scuds (orange, gray best), sowbug (tan or pink with hot orange beads best), San Juan worm, red or purple beaded North Fork Specials, pheasant tails, zebra midges, etc., and fish these under a strike indicator or by utilizing tight line nymphing techniques. Or, go small and fish dry flies using olive or gray sparkle duns, rusty spinners, black or brown caddis, Griffith’s gnats, para-emergers, etc. Most importantly, don’t be afraid to switch things up as daylight hours continue to shorten during October and November.

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