How to Identify Largescale Sucker

To identify Largescale Sucker (Catostomus macrocheilus), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Dorsal surface typically dark olive to brownish-gray, fading to silvery or yellowish-white on the ventral side. Sides may have a brassy or coppery sheen. Fins are usually dusky or yellowish.

Scale type

cycloid

Mouth position

subterminal

Distinctive features

Large, cycloid scales (49-68 in the lateral line), Subterminal mouth with thick, papillose lips, Absence of a lateral stripe in adults, Single dorsal fin with 10-13 rays

Dorsal fin

Single, relatively short dorsal fin with a straight or slightly concave margin, typically 10-13 soft rays.

Tail fin

Moderately forked caudal fin.

Pectoral fin

Pectoral fins are relatively large and low-set.

Distinctive fins

Pelvic fins are abdominal, located well behind the pectoral fins.

Identification Tips

1. 1

   Scales

   Count the scales along the lateral line; Largescale Suckers typically have 49-68 scales, which are noticeably larger than those of many other sucker species in their range.

2. 2

   Mouth

   Observe the mouth position and lip structure. The mouth is subterminal (located on the underside of the head) with thick, fleshy, and distinctly papillose (bumpy) lips, which are characteristic of bottom feeders.

3. 3

   Dorsal Fin

   Note the single dorsal fin, which usually has 10-13 soft rays. The anterior rays are typically longer than the posterior ones, giving the fin a somewhat triangular shape.

4. 4

   Body Shape and Coloration

   Adults have a robust, cylindrical body. Coloration is generally dark olive to brownish-gray dorsally, fading to a lighter, often silvery or yellowish, ventral surface. Absence of a prominent lateral stripe in adults helps distinguish it from some other sucker species.

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