Match the Hatch: Streamers

Understanding insect life cycles is a core concept in most freshwater fly fishing. It’s hard to find an introductory book that doesn't discuss the development of mayflies, caddisflies, and stoneflies. But what about all the other common creatures that live in rivers? Let’s take a look at some important life cycle details for sculpins, whitefish, suckers, minnows, crayfish, and several other animals that frequent a typical trout stream. We compiled the basics, fly recommendations, and stick around to the end where we conclude with some take-homes for the streamer angler.

All images credited to Woodling, 1985 unless otherwise cited.


Sculpins (USFS, 2022):

  • Live to 6 years

  • Sexually mature at 2 years

  • adult size: 5-6 inches

  • Diet 99% invertebrates

  • Also eat trout eggs, sometime other fish

  • Behavior mainly nocturnal (especially in summer)

  • May be active during the day when food is scarce (winter)

  • No swim bladder, so they sink when not actively swimming

  • Spawn in April and May

  • 5.6-16.7°C

  • 42.1-62.1°F

  • Males are territorial about nests

  • Females visit males nests

  • Big males and good nests are desirable traits

  • Baby sculpin leave guarded (male) nests after 8 weeks

  • Evidence that they are absent below dams but remain above dams if historically distributed in the system before damming (CPW, 2014)

  • FYI Colorado Anglers: There are no mottled sculpins east of divide in CO

Recommended Flies:

Adult: Slumpbuster, Sculpzilla, Zoo Cougar (Black, Olive, Brown, Yellow)

Juvenile: Guide's Choice Hare's Ear, Sparrow, Muddler Minnow

Image: Wikimedia Commons

Whitefish (Boyer, 2016):

  • Live to 15+ years

  • Sexually mature at 3 years

  • adult size: 24 inches

  • Diet similar to trout with a benthic (bottom oriented) bias

  • Spawn in October and November

  • Start migrating downstream for spawning in October

  • Stage during day and spawn at night

  • 0.0-13.3°C

  • 32-56°F

  • Juvenile whitefish hatch in early spring and school together in silty backwater adjacent to high flows

Recommended Flies:

Adult: Lil Kim, Sparkle Minnow (Grey, Silver)

Juvenile: Black Nose Dace Bucktail, Baby Rainbow Bucktail


White Suckers (Nature North, 2022):

  • Live to 15+ years

  • Sexually mature at 3-4 years

  • adult size: 16+ inches

  • Spawn in Spring

  • Temperatures starting at 10°C (50°F)

  • Eggs hatch in 2 weeks

  • Juveniles reach 5cm by 1 year old

Recommended Flies:

Adult: Sparkle Minnow (Gold, Silver)

Juvenile: Black Nose Dace, Mickey Finn


Crayfish (Fitzgerald, 2006; Meyers, 2006):

Rusty crayfish pictured, invasive in the western US
Image: Wikimedia Commons.

  • Live to 2 years

  • adult size: 3-5 inches

  • Forage primarily at night (nocturnal)

  • Molt 6-10 times in 1st year

  • 3-5 times in 2nd year

  • Mate in Spring

  • Juveniles hatch in 4-6 weeks

Recommended Flies:

Adult: Barr's Meat Whistle , Near Nuff Crayfish (Black, Rust, Olive)

Juvenile: Stonedaddy, Hell Razor Leech


Rodents (Salomone, 2022):

  • Live up to 6 years

  • Most rodents are nocturnal

  • When ranchers hay their fields (Memorial Day through early fall) it can displace mice near streams adjacent to pasture land, and they end up in streams from the chaos

  • Torpor (hibernate) in winter

  • Active foragers to prepare for winter

Recommended Flies: Morrish Mouse, Hood Rat


Frogs (Hoskins, 2019):

  • Live beyond 10 years (depending on species)

  • Sexually mature by 16 weeks

  • Undergo complete metamorphosis

  • Juveniles aquatic, Adults terrestrial

  • Mate in Spring

  • Tadpoles hatch 1-3 weeks later

  • Hibernate in Winter

Recommended Flies: Poppers, Deer Hair Poppers, Dahlberg Diver


The information on the following groups of fish are less detailed, but could still be relevant depending on your local streams.

Minnows (Woodling, 1985):

Ex: Stoneroller, fathead, brassy, suckermouth

  • Spawn in Spring

  • 15°C

  • 60°F

  • adult size: 3-6 inches

Recommended Flies:

Adult: Muddler Minnow, Mickey Finn, Autumn Splendor

Juvenile: Guide's Choice Hare's Ear, Sparrow


Darters (Woodling, 1985):

Ex: Iowa, Johnny, Arkansas

  • Likely spring spawn

  • adult size: 2-3 inches

Recommended Flies:

Adult: Baby Brown Trout Bucktail, Muddler Minnow

Juvenile: Guide's Choice Hare's Ear, Sparrow


Dace (Woodling, 1985):

Ex: Longnose, Speckled (abundant in CO)

  • Breeding Season between April and August

  • Breeding males are brightly colored

  • Adults up to 3.5” length

  • adult size: 2-5 inches

Recommended Flies:

Adult: Black Nose Dace

Juvenile: Guide's Choice Hare's Ear, Sparrow


Shiners (Woodling, 1985):

Ex: Bigmouth, Red, Common, Sand, Golden

  • Spawn in summer between July and August

  • adult size: 1-3 inches

  • Golden Shiner: 3-6 inches

Recommended Flies:

Adult: Sparrow, Muddler Minnow

Juvenile: Guide's Choice Hare's Ear


Other suckers (Woodling, 1985):

Ex: Bluehead, Flannelmouth, Longnose, Mountain

  • Spawn in Spring-Summer

  • Can live up to 20 years

  • adult size: 7-16 inches

  • Mountain sucker: 3-6 inches

Recommended Flies:

Adult: Sparkle Minnow (Gold, Silver)

Juvenile: Black Nose Dace, Mickey Finn


Sticklebacks (Woodling, 1985):

  • Spawn in Spring

  • 18.9°C

  • 66°F

  • Males make nests and

  • females move in to spawn

  • adult size: 2-4 inches

Recommended Flies:

Adult: Zonker, Woolly Bugger, Black Nose Dace

Juvenile: Bucktail, Guide's Choice Hare's Ear, Sparrow


Chubs (Woodling, 1985):

Ex: Flathead chub

  • found in CO’s Arkansas River

  • Spawn in spring

  • 1” long by late May

  • Ex: Fathead Minnow

  • Spawn in late Spring through early Fall

  • 18.3°C

  • 65°F

  • Sexually mature at 2 years old

  • adult size: 6-10 inches

Recommended Flies:

Adult: Sparkle Minnow, Woolly Bugger (Silver, White)

Juvenile: Baby Fat Minnow, Sparrow, Muddler Minnow, Guide's Choice Hare's Ear


Takeaways for Streamer Fishing

  1. Streamer fishing and night fishing are made for each other during Summer

  2. Big influx of eggs, and young of year fish in Spring

  3. Wet flies and bucktails in Spring might match young of year fish profiles better than bulky streamers

  4. As Fry emerge in Spring and grow into parr, opportunities exist to swing soft hackles and bucktail streamers

  5. Jigging action important to mimic sculpin behavior (lack of swim bladder)

  6. Look for bumps in flow to displace smaller fish

  7. Big articulated flies are better suited for Fall

  8. Late winter can see emergence of sac fry and Orange can be a good throat color for wet flies and streamers