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<br />..,
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<br />"'" -.
<br />..., ,;X;, " t:1i'~~' {'
<br />l...~ l.~;oJ~ ;" ,~...\. v ' ,,:c: _
<br />'f- ~.- '" ,;~.{.-"", , -"""'< ;..,~; ""- . ,..~,
<br />'"<; .,- '~< ~i~ . ,,_....... -
<br />~~4-"-J "~ ~- :Y"I~ _~~,~~~
<br />... _' '~~:Y"~~ '. ... '~~;~ "
<br />'. · '. ", ..:;;> .,lIo'.."" ....., ,,--. ..... _, _' "'--~_ ..
<br />· ,~",' <; ,.. f .~ ." ,
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<br />.-",c ~ - -~..... C'" - , ~ <-:- _ "-_"
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<br />
<br />Figure 29. Male (left) and female (right) loach minnow/chara/ito adornado, 62 and 57
<br />mm in total length, respectively, from Aravaipa Creek, Arizona. This unique, bottom-
<br />dwelling minnow is listed as threatened.
<br />
<br />ancient White River drainage of eastern Nevada (see
<br />below). These are relatively large, silvery minnows,
<br />commonly ranging to 125 mm long, that are trout-
<br />like in behavior and ecology. Both inhabit quiet
<br />water of pools and eddies below riffles and runs, eat
<br />aquatic insects and other invertebrates, and spawn in
<br />spring and summer. Male breeding colors are mostly
<br />seen as yellowish or reddish orange pigments at the
<br />bases of the paired fins.
<br />The loach minnow (Fig. 29) is the most secretive
<br />yet conspicuously colored minnow species in western
<br />North America. Males become brightly pigmented in
<br />breeding season (March through September), with
<br />colors ranging from blood red to brilliant orange on
<br />the lips, fins, and bodies. Females remain relatively
<br />drab, but develop yellow pigments on the fins and
<br />body. Males appear territorial and defend nests
<br />beneath stones on riffles. The species is small, with a
<br />large male rarely exceeding 65 mm long. It lives no
<br />more than two years, disappearing the third summer
<br />after hatching. The habitat is special (Fig. 30),
<br />
<br />
<br />consisting of riffles no more than 15 cm deep over
<br />gravel bottoms, and often in association with dense
<br />beds of coarse, filamentous algae. Life is spent on
<br />the bottom since the air bladder is greatly reduced
<br />and their body density is such that midwater
<br />swimming is labored and seemingly takes a great
<br />amount of energy. This fish feeds almost exclusively
<br />on mayfly and blackfly larvae, invertebrate co-
<br />inhabitats of its riffle habitat.
<br />Of all native fishes in the Southwest, the speckled
<br />dace is the most spectacularly variable in morphology
<br />and pigmentation (Fig. 31), as well as in ecology. It
<br />remains widespread throughout the Colorado River
<br />system, where a special kind adapted for life in canyons
<br />of the upper river is duplicated in other erosive
<br />habitats such as the Salt River Canyon of east-central
<br />Arizona. Even the Paria River, a small tributary
<br />entering the Colorado upstream from Marble Canyon,
<br />has a special form that is elongated, depigmented,
<br />with large fins and reduced, embedded scales
<br />(Fig. 31, lower). The Paria River is sand bottomed,
<br />
<br />
<br />Figure 30. Left: Loach minnow/charalito adornado habitat in riffles of Aravaipa Creek,
<br />Arizona. Right: Typical positioning response to swift currents over mixed gravel/cobble
<br />substrate.
<br />
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