The short answer
- No rises: fish a nymph. Aquatic insects spend most of their lives underwater, and so does most of the feeding.
- A dorsal fin or a back breaking the surface: trout are eating emergers just under the film, not dry flies.
- Busy rises in a caddis hatch with no adults taken: trout are chasing the pupae on their way up.
- Quick, firm takes to upright, cloudy-winged mayflies: duns. A Parachute Adams or a Comparadun.
- Soft, almost silent rings very early or late in the day: spinners lying flat on the water.
- When in doubt, lift an insect off the water and look at its wings, its size and its color.
What is a hatch, and what do trout eat during one?
In fly fishing, a hatch is the stretch of time when many aquatic insects emerge at once and become easy food. A rise does not always mean a trout is eating a dry fly. During a hatch, trout can be taking nymphs drifting off the bottom, emergers on their way up, adults that have just hatched or adults coming back to lay their eggs, and each one calls for a different fly. Each insect goes through it differently:
Mayflies
Nymph · emerger · dun · spinner
When a hatch begins, trout feed on the emergers; if it lasts and duns are plentiful, they move on to the duns. After mating, the females return to lay their eggs and trout eat them again, as they land and when they lie spent on the surface.
Caddis
Larva · pupa · adult
Adults fly off almost as soon as the pupa reaches the surface, so the feeding frenzy is usually on the rising pupae. Adults matter again a couple of days later, when they return to lay eggs: some skitter across the water, some dive under it and many sit on the surface to drop their eggs.
Stoneflies
Nymph · adult
Most nymphs crawl out onto the bank to hatch instead of rising through the surface, so they reach trout along the edges. Around Aysén, guides still fish big stonefly dries in November and December.
Damselflies and dragonflies
Nymph · adult
The nymph is the stage that matters most. Damsel nymphs migrate toward shore to hatch in late spring and early summer, and egg-laying damsel females are slow, easy prey on warm afternoons in January and February.
Read the rise: what you see and what to tie on
The first clue is where the take happens: on the surface, just under it or nowhere in sight. Then confirm it with what is on the water: insects, wings, empty nymph skins.
| What you see | What trout are eating | What to tie on |
|---|---|---|
| No rises, nothing on the water | Nymphs drifting or crawling on the bottom | A weighted nymph near the bottom; in lakes, along the weed beds |
| A dorsal fin or a back breaks the surface, and no insect disappears | Emergers a few millimeters under the film | An unweighted emerger such as a Flymph |
| Busy, energetic rises during a caddis hatch, but no adults taken | Caddis pupae rising to the surface | A Soft Hackle or a Sparkle Caddis Pupa |
| Quick, firm takes to upright flies with cloudy wings | Mayfly duns | A Parachute Adams or a Comparadun, #12–18 |
| Soft rings, almost silent, very early or late in the day | Mayfly spinners, flat on the water | A spent spinner with spread wings, #12–18 |
| Big caddis running across the surface of a lake | Adult caddis skittering after the hatch | An Elk Hair Caddis cast short from the boat and skated with the rod tip |
| Trout along the banks of a fast river, with nothing hatching | Stonefly nymphs crawling ashore to hatch | A weighted stonefly nymph close to the bank |
| Big nymphs swimming along the weed beds of a lake | Damselfly or dragonfly nymphs | A damsel or dragon nymph, stripped |
Trout and insect behavior follow a Chilean aquatic entomology guide for fly anglers (Sandoval, Ríos y Senderos, 2001–2003), written for all of Chile rather than for Aysén; dry-fly sizes come from an Aysén guide's hatch chart (Heinonen, Kalakamu). Tendencies, not rules: what is on the water decides.
How do you tell a dun from a spinner?
Both are adult mayflies. The dun, or subimago, has just hatched; the spinner, or imago, is the mature adult that comes back to the water to lay its eggs. The surest test is to lift one off the surface: cloudy wings mean a dun, clear wings a spinner. On the water, duns ride upright like small sailboats, and spent spinners lie flat with their wings spread.
Watch the trout too. Duns are drying their wings and could fly at any moment, so trout take them quickly and with some force. Spinners are going nowhere, and trout sip them calmly: barely a ring, almost no sound. Adult mayflies do not feed; they live from a few hours to a few days, mate and die, which is where the name ephemeral comes from.
Wind or turbulence sometimes drowns freshly hatched duns, which then drift a few centimeters under the surface. That happens more often than anglers admit, and a classic winged wet fly such as the Hare's Ear Wet covers it.
| Trait | Dun | Spinner |
|---|---|---|
| Wings | Cloudy, opaque | Clear |
| On the water | Upright, like a small sailboat | Flat, wings spread once spent |
| The rise | Quick and firm | A soft ring, almost silent |
| When | Any hour, any weather | Very early morning or the end of the day |
| Fly | Parachute Adams, Comparadun, #12–18 | Spent spinner, #12–18 |
How do you fish an emerger?
The emerger is the shortest stage and the most vulnerable: the nymph rises to split its skin a few millimeters under the surface, and trout know it. Those rises are easily mistaken for trout eating duns. The giveaway is the dorsal fin: when the fin or the back breaks the surface and no insect disappears, the trout is feeding under the water, not on top.
Emerger patterns look like an unweighted nymph, so they ride high, sized to the most active insect of the moment. The Chilean guide singles out the Flymph, championed by the American writer Dave Hughes, as one of the most versatile flies fished in Chilean waters. Cast upstream on a floating line and mend to kill the drag. Once the line has straightened, lift the rod tip slowly until you can almost see the fly: most takes come during that lift.
For caddis, fish a pupa when the surface is busy and you cannot see trout eating adults: trout often feed harder on rising pupae than on adults sitting on the water. Cast a Soft Hackle down and across, do not retrieve, and let it swing through the tail of a pool. Gary LaFontaine's Sparkle Caddis Pupa copies the air bubbles that carry the natural to the surface. The rest of the subsurface box is in our guide to the best nymphs for Coyhaique.
When do trout rise around Coyhaique?
An Aysén guide's hatch chart puts the stonefly peak in November and December, caddis in December and January and mayflies in January and February. The same guide describes late evenings when trout could be heard rising with nothing visible landing on the water: exactly the moment for an emerger or a pupa. The dries for each hatch are in our dry-fly guide, and the hour-by-hour picture is in the best time of day to fish.
Reading rises is easiest on flat, clear water, where every take shows. Our spring creek guide covers the presentation that water demands. On the river, your guide reads the rise with you before choosing the fly, and flies are included in both of our programs.
