The kinetics of the antibody response to Aeromonas salmonicida were determined in sunshine bass (hybrid striped bass: female Morone chrysops X male Morone saxatilis) acclimated to 10, 18, 24, 29 degrees C, and to 0.15 mg 1(-1) un-ionized ammonia and 200 mg 1(-1) nitrate levels. Temperature and water quality factors affected the immune response of sunshine bass. Temperatures of 10 degrees C and 18 degrees C decreased the magnitude and delayed the time of the antibody response to A. salmonicida. The antibody response was not affected at 29 degrees C, which is above the optimal temperature for sunshine bass. Elevated un-ionized ammonia concentrations of 0.15 mg 1(-1) also did not affect the antibody response. Elevated nitrate levels of 200 mg 1(-1), however, decreased the antibody response to the same extent as 18 degrees C water.