Effects of temperature ($13{pm}1.5^{circ}C$, $23{pm}1.5^{circ}C$) on the pharmacokinetic properties of nalidixic acid (NA) and piromidic acid (PA) were studied after oral administration to cultured black rockfish, Sebastes schlegeli. Serum concentrations of NA and PA were determined using HPLC-UV detector after a single dosage of 60 mg/kg body weight. At $23{pm}1.5^{circ}C$, the peak serum concentrations of NA and PA, which attained at 24 h post-dose, were 5.87 and $0.43;{mu}g/ml$, respectively. At $13{pm}1.5^{circ}C$, the peak serum concentrations of NA and PA, which attained at 10 h post-dose, were 6.22 and $1.57;{mu}g/ml$, respectively. Better absorption of PA was noted at $13{pm}1.5^{circ}C$ compared to $23{pm}1.5^{circ}C$. However, absorption of NA was not affected significantly by temperature. The elimination of NA and PA from serum of black rockfish was considerably faster at $23{pm}1.5^{circ}C$ than at $13{pm}1.5^{circ}C$. The kinetic profile of absorption, distribution and elimination of NA and PA in serum were analyzed by fitting to a one compartment model, with WinNonlin program. The AUC, $T_{1/2}$, $T_{max}$ and $C_{max}$, respectively, were: $161.25;{mu}g{cdot}h/ml$, 0.15 h, 12.29 h and $8.91;{mu}g/ml$ at $23{pm}1.5^{circ}C$, and $134.12{mu}g{cdot}h/ml$, 0.18 h, 8.79 h and $5.00;{mu}g/ml$ at $13{pm}1.5^{circ}C$ with NA; $41.57;{mu}g{cdot}h/ml$, 0.58 h, 8.24 h and $0.21;{mu}g/ml$ at $23{pm}1.5^{circ}C$, and $40.36;{mu}g{cdot}h/ml$, 0.59 h, 5.04 h and $1.20;{mu}g/ml$ at $13{pm}1.5^{circ}C$ with PA.