Fly Fishing Knowledge: What Do Trout Eat | Trout Diet

Trout are known to feed on aquatic insects such as flies, mayflies, caddisflies, and stoneflies as well as crustaceans such as shrimp, scuds, and sowbugs. But, this question is not commonly asked to "feed" the trout. Anglers ask this to lure the trout with their favorite flies. Also, this can help in locating the big trout population in a river. Trout are known for their ability to eat almost anything smaller than themselves that they can fit in their mouths. This also includes creatures that accidentally fall into the water from the shore, such as crickets, mice, and other small animals.

Crustaceans

Trout feed on several crustacean species (shrimp, crayfish, and water fleas), but it's not their main source of diet. They rely on aquatic insects and also consume small fish as an important part of their diet:

Stoneflies
Caddisflies
Mayflies
Mysis shrimp

Crustaceans inhabit both saltwater and freshwater environments, including inland brines with higher concentrations of salt than seawater. They can free-swim or burrow under rocks, sediment, or seaweed to survive in these environments. Moreover, it’s important that you understand how to read water. This helps find the insects that trout feed on.

Stone flies for Cutthroat Trout

This is one of the best baits for trout. They are mostly found in clean and oxygenated water that supports trout health; their nymphs provide delicious meals. When stoneflies emerge during wintertime, they can ignite an all-out feeding frenzy among trout.

Stoneflies differ from mayflies and caddisflies in three key ways:

Life Cycle Timing: Stoneflies hatch later (often winter into early spring), while mayflies and caddisflies are more common in warmer months.
Nymph Behavior: Stonefly nymphs crawl out of the water to emerge, unlike mayflies and caddisflies that hatch on the surface.
Wing Position: Adult stoneflies hold their wings flat over their backs, while mayflies hold theirs upright and caddisflies tent them roof-like.

Pro Tip: Stonefly patterns are reliable choices, no matter the season. In winter and early spring, try using small black nymphs.

Caddis Flies for Brown Trout

Caddis species are mothlike insects with aquatic larvae that complete their full life cycles before becoming adults. They are a good food source for trout in clean and cold streams with fast current. As with other aquatic insects, they are found in a wide variety of freshwater environments. Their larvae feed on detritus, algae, and organic matter, while some even prey upon other invertebrates.

Caddisflies form portable protective cases made from sand, gravel, or plant debris to keep themselves floating along in water films. When they emerge as adults, they shed this shell and swim up to the surface, where their wings develop before flying off into flight. Learning how to use a fly fishing rod is as important as choosing the right flies.

Midges for Brook Trout

Midges are an essential year-round food source for trout. With bright red hues due to hemoglobin production, their larvae thrive on organic debris at stillwater bottoms, where they feed upon it.

Anglers love midge hatches as these adults develop wings to enable flight. Trout are known to eat the larvae and adult flies, as well as mayflies, caddisflies, and stoneflies, in addition to other aquatic insects.

Crayfish are an integral food source for trout in both spring creeks and tailwaters, where they congregate. Both predatory brown trout and rainbow trout consume this source of sustenance.

Leeches

Leeches might not look appetizing to us, but to a hungry trout, they’re like a steak dinner. They stay/ active year-round and can be found in slow-moving sections of rivers. They swim with a pulsing, undulating motion that makes them easy targets for hungry trout.

In fly fishing for catching trout, leech patterns are a must-have in your box. They’re deadly in stillwaters, particularly during low-light hours when trout are cruising for an easy meal. Black, brown, and olive are the go-to colours, and a simple strip retrieve can often trigger aggressive strikes.

Pro Tip: If the bite slows down, try fishing a smaller leech pattern under an indicator. Sometimes a subtle, suspended presentation is all it takes to fool a wary rainbow.

Mayfly Species

There's no discussion about the aquatic insects that trout feed on. They are found in nearly every clean stream and river. Plus, they hatch in staggering numbers and bring even the wariest wild trout to the surface. Their nymphs live along the streambed, clinging to rocks and vegetation, making them a constant food source.

When they emerge, trout of all sizes take notice, especially large brown trout, which often key in on drifting mayfly nymphs and emergers. Dry fly fishing during a mayfly hatch is one of the most exciting ways to target other trout species.

Pro Tip: Pay close attention to the size and colour of the mayflies on the water. Trout, especially those picky wild trout, can get selective fast. Matching the hatch closely can make all the difference in fooling a rising fish.

Wrapping It Up

At the end of the day, trout aren’t picky eaters; they’ll chow down on just about anything smaller than themselves. That’s what makes fly fishing so fascinating. Matching what they’re eating at the right time can turn a slow day into one you’ll be bragging about for years. So, next time you’re out there, think like a trout. Chances are, they’re feeding on something close by.

Book Your Fly Fishing Adventure with Frontier Anglers TN

Reading about trout diets is one thing - seeing it play out on the river is another. Frontier Anglers TN lives it every day on the water. Our fly fishing guides know these rivers inside and out, from the South Holston to the Clinch River, and they’ll put you in the best spots to take advantage of whatever the trout are feeding on that day. Think of us as your shortcut to the kind of knowledge that usually takes decades to build. So, contact us now!

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Fly Fishing Knowledge: What Do Trout Eat?