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into deeper areas. Preferred temperature is not known, but as water temperatures approach 30°C woundfin leave the shallow water areas and congregate in deeper portions of the stream (Lockart, pers. comm., 1977). Larval and post-larval woundfin appear to live inshore upon hatching, remaining in back waters and along the shoreline in a few millimeters of water, then moving with growth into deeper and swifter areas. Woundfin are found only in those tributary streams which resemble the habitat in the Virgin River. The lower portion of LaVerkin Creek is the only known -~ tributary with such habitat. ASSOCIATED SPECIES in Vir th f g e rom At the present, up to 9 non-native fishes are known River system, along with 6 native forms. Plagopterus, however, is intimately associated with only 4 of the native fishes and one introduced generally are found alone over shifting sand bottoms, species. Woundfin _ but sometimes are accompanied by flannelmouth suckers Catostomus latipinnis and/or the desert sucker Pantosteus clarki. The mainstream form of speckled dace, Rhinichthys osculus, typically occupies areas lateral to habitats of woundfin, and is most abundant near spring inflows and tributary mouths. Pantosteus clarki shows a marked proclivity for swifter waters and more solid substrates than woundfin, and the flannelmouth is character- istic of deeper, slower waters behind boulders or other. debris. The fourth native form, Gila robusta seminuda, occurs in the deepest pools, again lateral to Plagopterus habitat. The Virgin spinedace Lepidomeda m. mollispinis might be considered almost as closely associated with woundfin as speckled dace, but is more restricted to spring inflows and creek mouths than is the woundfin or the dace. The red shiner, Notropis lutrensis, largely replaces woundfin where they occur together in temporary reaches of the Virgin River. Red shiners occur sympatrically with woundfin in the Virgin River near Littlefield, Arizona, where shiners are rare and Plagopterus usually common. The habitat here is relatively undisturbed. These data may indicate that in unmodified habitat woundfin maintain a competitive advantage over the introduced red shiner or merely indicate habitat preferences. The exact mode of interaction between these two species is unknown and presently under study. such as kin fishers Predators on woundfin include piscivorous birds g and herons, soft-shelled turtles and other vertebrate species. This is especially true during periods of low flow and clear water. Fish that feed on woundfin doubtless include Gila robusta seminuda as a potential predator on all life-history stages, and Lepidomeda m. mollispinis as a predator on larvae and fry. The introduced largemough bass (Micropterus salmoides) and green sunfish (Lepomis cyanellus) in the mainstream of the Virgin River are usually relatively small, limiting predation by them to larvae and young. Channel catfish (Ictalurus ~unctatus), while rare in the Virgin system, may prey on all life-history stages.