spawning was to occur, all fish were netted out of their treatment were not significantly different; therefore tanks. A tank insert with a false bottom was placed into we pooled the data. Whole-body cortisol was signifi- the treatment tanks, which allowed eggs to fal cantly higher in the stressed groups compared to the through the bottom. Each group of fish was returned to control and cortisol-fed groups at both Week 1 and its respective tank. Spawning occurred the next day Week 6 PE (Fig. 1B). There were no significant differ after the lights came on. Fish were then removed from the tank inserts and placed back into the tanks 161 A 00D5·33·100㎍g-1 feed Statistics. Statistical analyses were performed using S-PLUS 7 software (Insightful). In each analysis, nor mal distribution of the data was determined by plot- ting the residuals and verifying linearity. For the pre- liminary compared mean cortisol values of each dosage group using an analysis of variance (ANOVA) with Fisher’s least significant difference (LSD) test. For whole-body cortisol, weight, length, xenoma area, and myositis score, duplicate treatment tanks within each study were compared using a Welch’s modified t-test and pooled if there was no significant difference between the duplicates. Pooled cortisol, weight, length, xenoma areas, and myositis scores of different treatments within each study were compared using an ANOVA with Fisher’s LSD. We used Fisher’s exact tests to eval- uate the association between treatment group and prevalence of infection, mortality, and spawning suc- cess. We compared the number of the number of 5 dpf larvae produced by each treat- ment group using an ANOVA. The relationship between the number of eggs hatched larvae or the percent larvae hatched and infection intensity (xenoma area) was determined 5, 33 and 100 ug cortisol g feed for 0, 1,2, 4, and 6 wk. Let using regression analyses. The data were explained by ters over the SEM bars indicate a significant difference be- fitting a regression model to the data (y mx + b)’ tween cortisol dose groups at each time post-exposure (PE) to where y- eggs laid or hatched larvae or percent hatched and x- xenoma index, m slope of the line, and b-y-intercept. Significant differences were exposed to stress for 1 or 6 wk. Different letters over the SEM reported at α-0.05 12 10 6 4 2 cortisol-feed d ose-response study., we 20 2 Week post-exposure to cortisol feed 24 20 18 16 Week 1 OWeek 6 12 10 6 eggs produced and 2 No stress laid or the number of Fig. 1. Danio rerio. Cortisol-dose experiment (AB strain). (A) Mean whole-body cortisol (ng g+SEM after feeding fish 0, cortisol feed (there were no significant differences between cortisol dose groups at Weeks 0 or 1 PE. (B) Mean cortisol eng gSEM) in groups exposed to no stress, cortisol-fed, or bars indicate significant differences between groups (p< 0.05)