Once in experimental tanks, fish remained at 16–21°C for a 5-day acclimation period. All fish were then subjected to a 1-day intermediate exposure (Day-6; 18–23°C) prior to exposure to 3 days of heat cycling (Day 7–9; Tmax = 27°C in all treatments) with treatment-specific thermal minima. A fourth treatment group was maintained at 16–21°C throughout the experimental procedure. We ran two experimental trials, each lasting 9.5 days (Trial 1: 16–21°C and 22–27°C treatments, July 13–22; Trial 2: 18–27°C and 20–27°C treatments, July 22–31). Each thermal treatment was assigned a bank of three 300 L circular fiberglass tanks with each bank connected to separate recirculation systems. Parr were randomly selected from the holding tank (at 16–21°C) and transferred to one of the two tank banks (i.e. total N = 6 tanks). Fish were distributed equally among all experimental tanks (i.e. 108 fish per trial; ~36 fish per tank). For each sampling event, nine fish were sampled from a single tank within a bank. Sampling regimens were scheduled such that no tank was subject to consecutive samplings in order to eliminate recurring stress from repeated sampling within short time periods (minimum time between sampling a particular tank = 48 h). Fish were not fed 24 h prior to sampling.