7155

• UCREFRP Catalog Number: 7155
• Author: Holden, P. B., W. White and G. Somerville
• Title: Threatened Fishes of Utah
• USFW Year: 1974
• USFW - Doc Type: 51, Part 2
• Copyright Material: YES

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HOLDEN,ET AL.: THREATENED FISHES OF UTAH

~OradO River Fishes \

Ptychocheilus lucius-Colorado SquawfIsh

Status: Endangered species
Description: The Colorado squawfIsh is a large silvery fIsh that once,
attained sizes of 80-100 pounds and 5-6 feet TL. Body is pike-like with
long head and jaws, upper jaw reaching to near posterior margin of eye in
adults. Lateral line scales 80-95,9 dorsal and anal rays, pharyngeal teeth 2,
5-4, 2. Ught green or gray on back, silver laterally and white on belly. No
distinguishing sexual coloration, breeding tubercles cover body on both
sexes although finer on females. Often confused with round-tailed chub,
Gila robusta; however, adults can be separated by shorter jaw length of
chub; seldom reaching beyond middle of eye (Figure 1). Chubs are usually
darker dorsally, have orange or red coloration on breeding males, and are
more robust. Postlarvae of both species have a caudal spot, but that of the
squawfIsh is large and centered and that of the chub is below center and
small. The caudal spot is retained by juvenile squaw fIsh but lost in juvenile
chub.
Documentation: The Colorado squawfish originally occupied the entire
large river habitat of the Colorado River system. This included the states
of Wyoming, Colorado, Utah, New Mexico, Arizona, Nevada, andCaIifor-

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Figure 1. Colorado squawfish (top) and roundtail chub adults.

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