Jonathan Wood wrote:

Does anyone have experience keeping an Oscar without a heater?

I have some local fish in two tanks (50g and 125g) and the water is room
temperature (around 64). I was wondering if an Oscar could live in such a
tank.

Not without developing the urge to grow arms so it can grab you by the
front of the shirt and demand to know why $40 for a couple of heaters is
too much to ask.