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SummaryThe Virgin River chub (Gila seminuda) lives in the mainstream of the Virgin River from Pah Tempe (La Verkin) Spring, Utah to the Mesquite, Nevada river diversion (Holden and Golden, 2000). It is also found in the lower Moapa River in Nevada (Minckley and Marsh, 2009). Most adults live in the deepest water available; juveniles inhabit pools of water deeper than 18cm in depth (Minckley and Marsh, 2009; Williams and Deacon, 1998). The Virgin River chub is a unique hybrid species between (Gila robusta x Gila elegans) that evolved in the Pleistocene or post-Pleistocene era (DeMarais et al., 1992). It has a medium minnow size body with dorsal, anal, and pelvic fin rays numbering 9 to 10 (Minckley and Marsh, 2009). Body lengths reach from 15 to 25cm and has a head length divided by the depth of the caudal peduncle that is typically between 4.0 and 5.0 (AGFD, 2001; Minckley and Marsh, 2009). The back, breast, and belly have deeply embedded scales that typically lack basil radii (AGFD, 2001; Minckley and Marsh, 2009). Adults are generally omnivorous feeding primarily on filamentous green algae; juveniles consume mostly macroinvertebrates found within the river system (Cross, 1978; DeMarais et al., 1992; Greger and Deacon, 1988; Minckley and Marsh, 2009). Spawning, occurs from May to July when water temperatures have warmed near 24°C, and high turbid waters have subsided from 0.08 to 0.15 m/sec (Cross, 1978). Threats for this species include: lowered water flow from irrigation diversions, increased temperature and salinity levels, and invasion of non-native fish species like the red shiner, and its associated parasites (Cross, 1978; DeMarais et al., 1992). Current efforts to preserve and enhance habitat include: monitoring of water quality and flow rate, and aggressive removal of non-native fish. This species is currently classified as endangered under the Federal Endangered Species Act as of 1989.