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Results <br />No evidence of intra- or interspecific interference competition (i.e., <br />agonistic behavior) was observed in any of the experimental treatments. This <br />was consistent with previous observations made while rearing larval Colorado <br />squawfish and fathead minnow (D. W. Beyers, unpublished data). Lacking <br />evidence of interference competition, subsequent analyses were devoted to <br />study of intra- and interspecific exploitative competition. <br />Intraspecific exploitative comoetition <br />Maintenance of fish densities and relative abundances was problematic <br />because survival increased directly-with feeding regime. Mean survivorship in <br />32, 80, and 200 zooplankton•fish~~•day~~ feeding regimes was 68, 80, and 86 q <br />for Colorado squawfish and 34, 56, and 75 % for fathead minnow, respectively. <br />However, because the duration of the experiment was relatively short, it is <br />likely that initial densities and relative abundances were maintained for most <br />of the experiment. This assumption was supported by the consistent relation <br />between relative growth and feeding regime in single-species <br />assemblages (Figure 2). These relationships would probably have been more <br />variable if fish densities deviated from target numbers early in the <br />experiment. <br />Intraspecific competition in single-species assemblages diminished <br />(i.e., became less intense or severe) as zooplankton availability increased. <br />Relative growth of Colorado squawfish and fathead minnow increased <br />significantly (P = .0001 and P = .0003) with zooplankton availability <br />13 <br />