Matching the hatch in Aysén, Patagonia

This article is a mix of my own observations on the water and what I have learned from talking to local guides.

Nothing will replace your own observations on the water but this will help you be prepared with the right flies. Always trust your own instincts first.

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Hatch Calendar

Insect	Peak months	Key patterns	Hook sizes
Stoneflies	November, December	Fat Albert, Madam-X	8–12
Caddisflies	December, January	X-caddis, Streaking caddis	12, 14, 16
Mayflies	January, February	Parachute Adams, Comparadun, Found link	12–18
Terrestrials	February, March	Stimulator, Fat Albert, Chubby Chernobyl	4–10

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Stoneflies

Adult stoneflies show up in the Patagonian spring while the rivers are still running high. They don’t hatch on the water surface like mayflies or caddis. The nymphs crawl onto rocks and branches to emerge, and the adults can drop into the water from there. So fish close to the banks. Big rubber-leg stonefly nymphs are productive all season.

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Caddisflies

The caddisflies live up to a month out of the water. You can often see large quantities of caddis flying over the river without them ever touching the water. This is the caddis migrating. Trout usually eat the adult caddis when they are emerging, laying eggs or as spent caddis. Smaller trout sometimes jump out of the water to catch a caddis mid-flight. The larger fish don’t usually bother as it is not enough of a meal to justify an energy-costing jump.

I prefer the lower-riding X-Caddis and Streaking Caddis over the Elk Hair Caddis.

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Mayflies

There have been some late evenings in Patagonia where I could hear the trout rising to something but could not see anything hitting the water. Many times it is tiny size 18 mayflies so make sure to have some small ones in your box too.

Mayfly on the cabin wall — Aysén, January

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Terrestrials

Beetles, ants and hoppers are plentiful in Patagonia and the wind blows them to the water often. A big terrestrial is a welcome meal for the opportunistic trout. Don’t just dead drift these, a little movement can trigger a strike. A big Stimulator will catch fish most of the season even when nothing is hatching and you see no surface activity. Go big with these flies.

Cantaria Beetles

Also known as Darwin’s beetle. These things are huge (4-9cm in length). The male cantaria beetle has big jaws. Large foam flies are the standard imitator for Cantaria among the local guides but large deerhair flies work just as well.

Cantaria beetle, or Darwin’s beetle — Aysén, February

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Tactics for Dead Periods

Sometimes there are those days when nothing is happening on the surface. I firmly believe that there are always a few fish around that will take a dry fly no matter what. So my go-to on the slow days is a dry dropper rig. Big Stimulator or Fat Albert with a beadhead Pheasant Tail or Perdigon. Nothing wrong with going to tightline nymphing or using an indicator.