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Statistical Analysis We ran 29 trials to examine predation on exercised and unexercised (control) bony tail in small arena experiments. Numbers of bony tail varied from two to five pairs (control and treatment) offish; thus number of prey in each trial ranged from four to ten bony tail. Of these 29 trials, 22 resulted in unequivocal success (no ties) by either control or exercised bony tail. Thus the expected ratio under the flull hypothesis of random predation was 11: II. Exercised bony tail survived in 14 trials, whereas control fish survived in eight trials. However, we cannot reject the null hypothesis (one-tailed Goodness 01 Fit: X = 1,636, df = I; p = 0.143). Random Observations Clear water allowed us to observe the relative number, location, and behavior of fish in all the tanks during the initial phases of all tests. Routine observations were conducted early in the morning, mid-day, in the afternoon, and occasionally after dark. We were interested in prey behavior (for example, schooling) and their distribution relative to the proximity of predators in the 2-m, 4-m, and 7- m tanks, Water temperatures were periodically checked, and the water depth was maintained at 1 m. Bcha\ior changes were quite dramatic for both species as were the mannerisms of the predators themselves Largemouth bass generally fed during the day, which could be easily observed, but lIfltlll"lLlnately. flathead catfish were entirely nocturnal. In those trials, we could only observe pre- and pust-predatlon behaVior lor the razorback suckers. Bony tail Largemouth bass generally fed during daylight. When placed with the bass, bony tail would school and initially intermixed with the largemouth bass. They exhibited no apparent avoidance behavior. The largemouth bass would eventually start crowding the bony tail causing them to more tightly school. This could take a few minutes and in some cases hours, depending upon the degree of ~16gression exhibited by the bass. Prior to this series of experiments, predators were fed small nonnative fish salvaged from the rearing ponds. These included juvenile sunfish (Lepomis spp), threadfin shad (Dorsoma petenence), and common carp (Cyprinis carpio). When prey were placed in the circular tanks, they would immediately swim near the surface and against the tank's sides. This mimics the behavior of small fish that hug the shoreline when a predator was present. The potential angle (450) of attack is greatly reduced at this position. The only exception is where the tank sides meet the bottom; there, a predator can drive its prey into the tank's side. On the surface with no backstop, the prey had a better opportunity to escape. We witnessed the same behavior with bony tail that had been with predators for a length of time (rig 12) On closer examination, these fish often showed signs of bruising and missing scales, which ~uggested they survived an unsuccessful attack. One of us (GAM) witnessed two such attacks; both times the bony tail had escaped. This behavior was only exhibited when bony tail were with predators; it was never observed in the control tanks where bony tail schooled at the bottom. All evidence suggests this is a predator-avoidance behavior, learned through predator aggression or actual predation of another IJHJlvidual, 17