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Figure 52. Male (left) and female (right) whitefin pupfish/ cachorrito a/eta blanco, 47 and 39 mm in total length, respectively, from Ojo de Galeana (Ojo de Arrey), Chihuahua. Pupfish of this general morphology are also widely distributed in the upper Rio Yaqui basin; the form was not considered by the American Fisheries Society. Figure 53. Female (left) and male (right) of the endangered Gila topminnow/chara/ito, 45 and 30 mm in total length, respectively, from Monkey Spring, Arizona. depicted in Figure 52 is widespread in streams, springs, and marshes located in grass and woodlands of the northern Mexican Plateau east of the Sierra Madre Occidental. All known occurrences for the species are at elevations higher than abour 1400 m. Topminnows in both the Colorado and Yaqui basins are found from near 1500 m to sea level, although high-altitude occurrences are most commonly associated with outflows of springs. In the Colorado basin, the Gila topminnow/charalito (Fig. 53) formerly occurred from Frisco Hot Spring, New Mexico, to near the mouth of the Gila River; it was perhaps most widespread in spring-fed creeks and marshes of southern Arizona between 900 and 1500 m above mean sea level. In the Rio Yaqui basin, the Yaqui topminnow/charalito similarly lives in upper parts of the system, to be replaced by two other species near the river's mouth. As might be anticipated from the common name, topminnows live near the surface in shallow water, and are often associated with aquatic vegetation or other cover. They feed on small invertebrates such as mosquito larvae, microscopic plants, and sometimes detrital materials. Both pupfish and topminnows reproduce year around in the constant temperatures of springs, bur have strong spring-summer reproductive cycles in habitats with seasonally variable temperatures. Pupfish are highly territorial, with males defending small, circular patches of substrate against all other males, and against other species as well. Females remain aloof from males, living and feeding in 26