Ok,so winter is comming!

[Red Devil]

there is not rele a sudden temperature change here...
it drops down day by day...and the weather is quite predictable...its gonna turn very cold very slowly and then it will snow...
so no sudden drops in temperature..
i heard using heater in the tank harms fishes....so i was wondering if they will do without one...

It depends on what temperture the tank will remain and how much fluctuation.. if it is only a few degrees it is okay if too much of a drop then no good.. most tropical fish can be 76-80 degrees..depends on what kind of fish.. but this is the average temp...you may want to get some temp strips to keep an eye on the water temp...heater does not harm fish...like anything else if a heater goes wacko then it could suddenly go up to high... but anyone useing any equipment for tank should keep an eye to make sure everything is always working properly.

 

[jphillips2020]

All I'm saying if anyone of those tanks gets down to 41 degrees most of them will die if not all.

 

[benzjamin13]

You'll probably need heaters for all your tanks. It also depends on how cold your house gets or where ever your tanks are. My house stayed relatively warm in the winter and the water never dropped below 72F I only used my heater maybe 2 months out of the year.