Tilapia (O. mossambicus) grown from FW laboratory stock were
maintained at 24–28 °C at the UC Davis Center for Aquatic Biology
and Aquaculture. Seventy-two fish, averaging 228.6± 5.9 g in mass
(23.8± 0.21 cm) were transferred at a density of four fish per tank
(~8.3 g fish/L) to recirculating 114-L, glass aquaria fitted with airstones
and maintained at 25–27 °C for blood chemistry analysis. They
were fed commercial trout pellets ad libitum until 2 days before
sampling. Water was carbon-filtered to prevent ammonia accumulation
using Fluval filters (Hagen, Inc.) and salinity was monitored using
a light refractometer. For respirometry experiments, twenty-four fish
in total, averaging 220.5± 5.3 g, were allowed a 24-h period without
feed before a 12–24 h acclimation period to respirometers prior to
measurements. Water was aerated and biologically filtered to prevent
ammonia accumulation, while partial water changes were performed
every 1–2 days throughout the experimental time courses to maintain
water quality. Salinity was monitored using a light refractometer