How to Identify Roundtail Chub

To identify Roundtail Chub (Gila robusta), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Dorsal surface typically olive-green to brownish, fading to silvery or whitish on the ventral side. Fins are often dusky or yellowish. Breeding males may develop reddish or orange coloration on their fins and lower body.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Robust, fusiform body, deepest anteriorly and tapering posteriorly., Large, terminal mouth extending to or slightly beyond the anterior margin of the eye., Relatively small, rounded fins., Lateral line complete, with 50-65 scales., Pharyngeal teeth typically 2,5-4,2 or 2,4-4,2.

Dorsal fin

Short, with 8-10 rays, originating slightly posterior to the pelvic fin origin.

Tail fin

Moderately forked, with rounded lobes.

Pectoral fin

Relatively small and rounded, with 15-18 rays.

Distinctive fins

Pelvic fins are small, with 9-10 rays, and are located abdominally.

Identification Tips

1. 1

   Body Shape

   Look for a robust, torpedo-shaped body that is deepest near the head and tapers towards the tail. This distinguishes it from more slender Gila species.

2. 2

   Mouth Size and Position

   The mouth is large and terminal, extending to or slightly past the front of the eye. This is a key feature for distinguishing it from other chubs with smaller or subterminal mouths.

3. 3

   Fin Shape

   All fins are relatively small and rounded, particularly the dorsal and pectoral fins. The caudal fin is moderately forked with rounded lobes.

4. 4

   Lateral Line Scales

   Count the scales along the lateral line; Gila robusta typically has 50-65 scales, which can help differentiate it from other Gila species with different scale counts.

5. 5

   Habitat Preference

   Its preference for flowing, rocky riverine habitats is a strong indicator, especially when found in the Colorado River Basin.

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