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fishes needed for this study. Consequently, the largest aspect of the tagging study was conducted at this location. Five tagging and marking systems were selected and evaluated on several sizes of hatchery-reared Colorado squawfish (mean fork length [FL]=72 mm; SD=0.6; range 55-88 mm), razorback sucker (mean FL=110 mm; SD=7.5; range 84-217), and bonytail (mean FL=76 mm; SD=1.9; range 62- 116 mm). The five tagging and marking systems (experimental groups) evaluated included both physical (internal and external) and chemical types. These were: 1) PIT tags (two treatments), 2) V. I. (visible implant) tags, 3) Carlin-dangler tags, and 4) acrylic dyes. The two treatments of PIT tags consisted of those fish implanted with a PIT tag either in the body cavity or in the dorsal musculature. Sixty fish of each species comprised each of the experimental groups; sixty fish of each species were used for the control group (no tag or mark) (Figure 1). Carlin-dangler tags were attached to bonytail and razorback sucker only. Two different test environments were selected to hold the experimental and control groups for each of the three fish species. Experimental groups and controls for each species were equally divided (30 fish) between an outdoor earthen pond (approximately 0.04 hectare) and an outdoor cement raceway (14 m X 1.8 m X 0.6 m). The raceway and pond were continuously provided with ground water. The pond was covered during the fall and winter (October through April) with polypropylene netting (2.54 cm mesh) to control avian predation. All fish in each experimental group received a specific secondary mark (full fin removal) to allow recognition of potential tag/mark loss over time. All fish were anesthetized with tricaine methanesulfonate (MS-222) prior to fin removal. This was conducted approximately one week prior to the tagging/marking. The secondary mark for each experimental group was as follows, 5