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.' , squawfish (Table 4) which were captured from the Colorado River in May 1986 and held at Tiara Rado golf course pond approximately 3-4 months before they died in July and August, 1986. Levels of mercury found in the two Colorado River channel catfish were approximately equal to the 1980-81 NCBP mean for channel catfish #2, and approximately equal to the 85th percentile for channel catfish #1. Levels of mercury found in the three Colorado squawfish were all elevated, from 1.5 to 2.1X the NCBP 85th-percentile value. Colorado squawfish may have accumulated some mercury from the golf course pond. However, because these squawfish were probably much older than the channel catfish, they probably accumulated more mercury from the Colorado River. Colorado squawfish #7 contained a high level of selenium at 6.3 ug/g dry weight. Channel catfish from the Colorado River both had selenium levels below the 1980-81 NCBP mean value of 1.88 ug/g dry weight. It is possible that the squawfish #7 may have accumulated selenium from the golf course pond. Lemly (1982) noted a significant bioaccumulation of waterborne selenium by juvenile bluegills and largemouth bass within 120 days (exposed to 10 ug/1). Also, as in the case of mercury, squawfish may also have accumulated selenium from the Colorado River. Lemly (1982) also demonstrated a 50% excretion rate of selenium from centrarchid gills and erythrocytes, though there was essentially no elimination from the spleen, liver, kidney or muscle at 30 days. Colorado squawfish #7 also had a higher level of cadmium compared to the 1980-81 NCBP 85th-percentile level. Cadmium levels were low in the other two squawfish and the two catfish collected from the Colorado River. Uptake of cadmium is highly variable, depending on physiological, chemical and biological factors. Body burdens generally increase with size-and age of fish