We're honestly not trying to be mean here. This is just what these types of fish basically need.
I have a coldwater tank, and the fish need an extremely high current, plenty of oxygen, and a way to keep cool in summer. I'm lucky in that there's an HRV system in my house, and it keeps the room temp down, and subsequently, keeps the coldwater tank at 20C at the most. When I first started and was living elsewhere, the tank would easily get up to 24-25C even without a heater, and well out of the sun.
A coldwater tank is not just a tropical setup without a heater, these fish have their own requirements and certain compatibilities too, and you need to research those carefully.