the breeding season, the Colorado River cutthroat trout (O.c.
pleuriticus) is a striking crimson color along the lateral
line, ventral surface, and gill covers, often with equally
striking shades of orange and golden yellow laid over a yellowish
or brassy background color. These colors become darker with
and non-breeding adults typically have white bellies which
gradually take on color as fish increase in size. A variety
of forms of Colorado River cutthroat have been observed, with
specimens from isolated populations showing widely varying
patterns of coloration and spotting, reflecting long-standing
spotting pattern of fish from the uppermost Green River system,
for example, is more typical of interior cutthroat trout in
general --pronounced, rounded spots no larger than the pupil
of the eye, concentrated on the caudal peduncle and above
the lateral line anterior to the dorsal fin. Alternately,
fish from the Yampa River Basin, farther to the east and originally
abutting the Continental Divide, more closely resemble the
greenback cutthroat trout, with spots larger than the pupil
of the eye.
accounts indicate individual Colorado River cutthroat were
commonly as large as 20 lbs., whereas most adult fish today
are under 5 lbs. because of reduced habitat quality.