In streams, Rainbow Trout prefer water temperatures from 54°F to 66°F, while lake-dwellers select waters between 45°F and 64°F. The maximum tolerable water temperature is 77°F.
The temperature level in our TIC tank must also be right for the nitrogen-fixing bacteria that will convert fish waste into less harmful compounds. Most strains of nitrifiers grow optimally at temperatures between 77-86°F (25-30°C). Bacterial growth rate is decreased by 50% at 64°F (18°C) and by 75% at 46-50°F (7-10°C).