Tricos are the late-summer-into-fall mayfly that fish will gorge on at dawn. The hatch starts around sunrise, the spinner fall comes 1–2 hours later, and by 10 AM it's usually over.
What makes trico fishing distinct: density. Thousands of bugs blanket calm water in spinner falls, and trout sip in slow rhythmic patterns through the swarm. Use 6x or 7x tippet and a low-floating spinner pattern — these fish are inspecting carefully.