I have some koi fry that I brought in for the winter. They are still pretty small, biggest is 1 1/2 " smallest is 1/2". I didn't have a heater and was trying to get the tank cycled, temp dropped to 62, so I went and bought a Eheim thermo control 100 W. What is the maximum temp I should set it at? I know technically they don't need it, but someone told me it would boost their immune.
Here is a video
Here is a video