Freshwater Fish Identification Guide

Here's a breakdown of characteristics to help identify various freshwater fish species, listed alphabetically:

Black Crappie

  • Large rounded dorsal and anal fins.
  • Deep, narrow bodies.


  • Olive green to bluish with blue and orange lower body.
  • Vertical bars on each side.
  • Solid black gill opercular lobes.

Brown Trout

  • Brown or olive back with large spots.
  • Light brown to yellowish sides with large dark spots surrounded by blue-gray halos.
  • Tail with few spots.


  • Darkish-black to brown body.
  • Head not as flat as channel catfish.
  • Brown or yellow cat-like barbels on mouth.
  • Scaleless skin.
  • No spots on sides.
  • Unforked tail.

Bull Trout

  • Characteristics similar to Dolly Varden.
  • Longer jaw.
  • Found in Eastern and Western Washington.

Channel Catfish

  • Blackish to silvery to white sides.
  • Small irregular spots possible.
  • Scaleless skin.
  • Cat-like black barbels on mouth and jaw.
  • Flat head and forked tail.

Coastal Cutthroat Trout

  • Variable body color.
  • Numerous closely grouped spots on dorsal fin and tail.
  • Maxillary usually extends beyond the back of the eye.
  • May have red or orange slash on underside of jaw.

Dolly Varden

  • Olive green to brown above and on sides.
  • Cream or pink spots.
  • Slightly forked tail.
  • Found in Western Washington headwater streams.

Eastern Brook Trout

  • Dark green or blue upper body.
  • White belly turning vibrant orange near spawning.
  • Wormlike markings on upper body and dorsal fin.
  • Yellow and pink spots with blue rings on sides.
  • White-tipped lower fins with square tail.

Grass Carp

  • Silvery to olive coloration.
  • Large scales without scales on the head.

Green Sunfish

  • Large mouths.
  • Three spines on the anal fin.
  • Dark spot at the base of the last three soft dorsal rays.


  • Non-anadromous form of sockeye salmon.
  • Blue backs and silver sides.
  • Finer scales and larger eyes compared to other trout.
  • No distinct dark spots on backs and tail fins.

Largemouth Bass

  • Dark green back and sides.
  • Dark horizontal band along sides.
  • White belly.
  • Large jaw extending behind the eye when closed.

Rainbow Trout

  • Variable body color.
  • Numerous closely grouped spots on dorsal fin and tail.
  • Maxillary usually does not extend beyond the back of the eye.

Rock Bass

  • Large mouths and reddish eyes.
  • Five or more spines in the anal fin.

Smallmouth Bass

  • Dark olive to brown on back.
  • White belly.
  • Bronze sides with dark vertical bands.
  • Small jaw not extending behind eyes.


  • Ocean-run rainbow trout.
  • Return after one to three years at sea.

Tiger Muskie

  • Long, cylindrical body.
  • Lobe-shaped dorsal and ventral fins near the tail.
  • Prominent duckbill-shaped snout.
  • Dark spots or vertical stripes/bars on a light background.


  • Black to brown coloration on a whitish background.
  • Whitish lower portion of the tail fin.
  • Dark spot on the first dorsal fin.
  • Elongated teeth.

Westslope Cutthroat Trout

  • Variable body color.
  • Numerous closely grouped spots towards dorsal fin and tail.
  • Maxillary usually extends beyond the back of the eye.
  • Red or orange slash on underside of jaw.

Yellow Perch

  • Greenish to yellow body with a white belly.
  • Vertical dark crossbars on each side.
  • No prominent teeth.
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