How to Identify Flannelmouth Sucker

To identify Flannelmouth Sucker (Catostomus latipinnis), look at these key features.

Physical Characteristics

Body shape

elongated

Coloration

Dorsal surface typically dark olive to brownish-gray, fading to a lighter, often yellowish or silvery-white belly. Fins are usually dusky. Spawning males may develop a reddish lateral band and nuptial tubercles.

Scale type

cycloid

Mouth position

subterminal

Distinctive features

Large, fleshy, papillose lips with numerous folds and papillae, particularly on the lower lip, giving it a 'flannel-like' appearance., Subterminal mouth, adapted for bottom feeding., Relatively large scales for a sucker species, with 60-75 scales in the lateral line., Dorsal fin typically has 11-13 rays., Caudal peduncle is relatively deep.

Dorsal fin

Single dorsal fin, typically with 11-13 soft rays, positioned mid-body.

Tail fin

Moderately forked caudal fin.

Pectoral fin

Large and somewhat rounded pectoral fins, positioned low on the body.

Distinctive fins

Pelvic fins are abdominal, located well behind the pectoral fins. All fins are generally dusky.

Identification Tips

1. 1

   Mouth and Lips

   Observe the large, fleshy, and highly papillose (bumpy) lips, especially the lower lip, which is deeply incised and appears 'flannel-like'. This is the most distinguishing feature.

2. 2

   Scales

   Count the scales along the lateral line; Flannelmouth Suckers typically have 60-75 scales, which are relatively large compared to other suckers in its range.

3. 3

   Dorsal Fin Rays

   Count the soft rays in the dorsal fin; usually 11-13, which can help differentiate it from some other sucker species.

4. 4

   Body Shape and Coloration

   Note the elongated, robust body and the typical dark olive to brownish-gray dorsal coloration with a lighter belly.

Explore Flannelmouth Sucker