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Severson et al. 59 over the remaining diets (AP-I00 and Dio-dry) because of its si~i- lar performance to them, cost, availability, and its widespread use in coldwater hatcheries. On day 71, fish fed A-250 were switched to A-400, a 400-Jj. granulation of the same formulation. The fish were hand-fed six times per day for a daily ration of 10% of total body weight. Feeding rate was adjusted at two-week intervals. Survival and growth was calculated at the end of each experimen- tal phase. Instantaneous daily growth (0) was calculated from ini- tial weight and final weight for each diet: o = (lo&: W2 - lo&: w,)/d where w, and W2 are the initial and final average weights, respec- tively, and d is the duration of study in days (Ricker 1975). One- way analysis of variance and Tukey multiple comparison tests were used to determine differences in fish growth and sUlvival (Sakal and Rohlf 1981) in Phase II. An arcsine transformation was applied to survival rates to more closely approximate normality. Statistical tests were not performed on Phase III because only one of the four treatments had replicat~s. At the end of Phase III, the fish were measured and examined for gross deformities, and five fish from each experimental lot were sent to the Bozeman Fish Technology Center, Bozeman, Montana for histological examination. RESULTS AND DISCUSSION ~ ".....-..:':'.,":........ ; Phase I (Day 5-25) - Survival was 96% (N = 3,359) for razorback sucker fry fed the B-250 diet for 20 days. Average fish weight increased from 0.005 g to 0.01 g (SD = 0.022), a daily weight gain of about 4% (0 = 0.038). These results were consistent with results from an earlier study (Tyus and Severson 1990) in which razorback sucker fry fed B-250 for 45 days had a survival rate of 78% and a daily weight gain of about 5% (0 = 0.046). The higher survival in this study was presumably because daily feeding rate was greater.