Crayfish

Latin: Pacifastacus leniusculus (Signal Crayfish — Western North America) Family: Astacidae (decapod crustaceans) Sizes (fly): #2 – #8 (large) Where: Throughout North American freestones and lakes; rocky bottoms with cover

Overview

Crayfish are big-meal targets — when a trout (especially a brown trout) eats a crayfish, that's a serious calorie haul. Crayfish are nocturnal, hiding under rocks and cover during the day and foraging at night. They walk and dart along the bottom, occasionally doing the characteristic backwards "tail flip" when threatened, which is exactly the action a stripped streamer mimics. The Kingfisher 6/10/2025 report noted "The Blackfoot is also home to large crawfish that trout love to snack on. JJ Specials in long strips or dead-drifted through the rocks can sometimes coax those larger fish out of hiding."

Life cycle and angler relevance

No hatch — crayfish are present year-round. Best fishing is dawn, dusk, and overnight conditions, or anytime in cloudy weather. Streamer patterns are the standard imitation; the strip is short-pause-short to mimic the natural backward dart. Best on rivers with abundant cobble bottom and slow-deep pockets.

Imitating patterns

JJ Special (signature crayfish streamer for Western rivers), generic crayfish streamer patterns (Clouser-style with claws), Whitlock's Near Nuff Crayfish, dark olive/brown bugger variants.

References

• Wikipedia: Signal crayfish
• Mentioned in 2025 Kingfisher Blackfoot June reports
• Field photo by Parsa Fard (CC-BY) via iNaturalist

Pacifastacus leniusculus (close-up)

Field photo (Vasona Reservoir, CA)