7621

• UCREFRP Catalog Number: 7621
• Author: Woodling, J.
• Title: Colorado's Little Fish
• USFW Year: 1985.
• USFW - Doc Type: A Guide to the Minnows and Other Lesser Known Fishes in the State of Colorado.
• Copyright Material: NO

STONEROLLER
Campostoma anomalum
(Rafinesque)
This species is slender when young,
maturing into a stout minnow; the mouth
is inferior, overhung by a bulbous snout;
lower lip fleshy which almost covers a
hard, plate-like lower jaw; 8 dorsal fin rays;
7 anal fin rays, lateral line scales usually
more than 50 (49-57); intestine very long
and coiled around the air bladder,
peritoneum is black; pharyngeal teeth 4-4.
Coloration changes with both age and
season. The young are silvery with a
dusky stripe on the sides while the back
and sides of adults range from silver to
tan or light brown with scattered black
spots. The lower sides and stomach of
adults are silver to white and adult males
have a dark stripe along the lower half of
the dorsal fin. Breeding males are con-
spicuous with distinct tubercles on head,
orange eyes, with an orange and black
stripe on the dorsal and anal fins. Adults
are commonly 3-7 inches in length with
males larger than females.
Range: Stonerollers are found from
Wyoming east to the Appalachians, south
to Alabama and west to New Mexico and
northern Mexico. In Colorado, stonerollers
are common in streams and rivers on the
plains east of the mountains and into the
foothills.
Habitat: Although more common in
permanent streams, stonerollers are
found in some intermittent plains
streams. The species is absent from
organically enriched stream reaches.
Found in both pools and riffles over a
sand-gravel substrate, stonerollers require
some current. Often seen in large swirl-
ing groups at the bottom of pools and
runs, this minnow will also concentrate
along the banks of streams in submerged
vegetation or other cover.
Starrett (1950) found the stoneroller in
Iowa fed on bottom ooze composed of
diatoms, fine sand and perhaps mud. The
long coiled intestine of stonerollers is an
adaptation common to plant-eating fish.
Reaching maturity in the second or third
year, stonerollers spawn in early to late
spring (Pflieger 1975) when water
temperatures exceed 60°F (Miller and
Robison 1973). In Colorado, stonerollers
have been observed spawning during the
first week of May in a spring-fed tributary
of the North Fork of the Republican River
in Yuma County. Males constructed nests
in shallow water of pools or riffles next to
deeper water, into which the fish fled when
frightened. The nests are irregular in
Family Cypnnidae Genus Campostoma
outline, several inches in diameter, and
close to each other. Several males appear
to work together building nests. The
males take gravel into the mouth and
transport it out of the nest, a vigorous
thrashing motion is used to dislodge fine
material which drifts away on faint water
currents. When females swim out of deep
water into a group of nests, one or more
males press against the female. Eggs are
then deposited, fertilized, buried and
abandoned. Creek chubs were often
observed to drive smaller stonerollers
from the spawning site and then nose
around the bottom of the nest, perhaps
feeding on deposited eggs. Orangethroat
darters also congregate around the edge
of stoneroller nests during periods of
spawning activity, perhaps looking for an
opportunistic meal.

1-- -
Distribution by County of the stoneroller.
r -r -JI

Colorado's Little Fish 20
Adult male stoneroller about six inches long.
Adult female stoneroller about five inches long.