I have a 55 gallon native tank that houses sunfish and a bullhead. I have a few plants in there that don't require a lot of light (sorry I don't recall the names, but I know they aren't java types). I don't light the tank directly and have no heat for it either. I am thinking of lighting half the tank for a few hours a day but have no intention of heating it. How is plant health affected by the water temp. I doesn't matter too much if they don't grow fast. I just don't want to kill them from it being too cold. The tank shouldn't get below 60 this winter. It is a little cooler than the air temp. About 65 - 70 F at the moment.