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swim bladder inflation and exogenous feeding. Despite statistically significant differences in lengths of larvae in some treatments, it is improbable that the small differences observed for either newly hatched (difference among mean lengths in treatments < 15%) or 7 d post-hatch larvae (difference < 5%) are of ecological significance. Different endogenous feeding rates between treatments may be the reason for differences in fish lengths. Times to developmental events and length measurements were recorded irregularly in the 30°C treatment due to low hatching success and poor condition of larvae and may be less accurate than those reported for the other treatments. Time of first hatch and swim bladder inflation may not represent the norm due to rare events (e.g., very early hatch or air bladder inflation in a single fish). The times to first feeding that I report are more reliable because most fish in a treatment chamber began to feed almost simultaneously, thus reducing the potential influence of rare events. Management implications.--Colorado squawfish apparently have complex adaptive strategies for reproduction in historically fluctuating riverine habitats of the Colorado River basin and tnay use discharge level and variation, and water temperature, as primary environmental cues to initiate reproduction (Nesler et al. 1988; Tyus 1990). In its unregulated state, flow and temperature regimes in the Colorado River basin varied dramatically across seasons and years. Given such variability, eurythermicity of embryos and early larvae is not surprising. Reduced summer water temperature is thought to be partially responsible for extirpation of Colorado squawfish in river reaches immediately downstream from dams (Holden 1979; Behnke and Benson 1983; Marsh 1985). Reestablishment of self- 18