I have had my Platy tank set up for a couple of months now (previously cycled without the fish.) When I bought them Pets at Home told me they could be kept in cold water because they are the Variatus variety. I have them in a tank without a heater the temperature is currently at 20 - 21C and drops to around 18 - 19C at night when the light turns off. I have a heater that came with the tank so not sure if I should put it in or not?
What temperature should they be kept at?
What temperature should they be kept at?