bullheads can live in about anything but 70 is good they'll stay pretty active. They just dont like it to hot. You should be good without a heater though room temp would be fine.
well my thermometer reads 60-65, is this good?
i read that 70-80 was ideal temp, but then i questioned that because they are a native coldwater fish. so i am confused now.
should i set the heater to 65/70 and let it come on when it drops at night?
Bullheads will literally survive in any conditions. I just cleaned out my outdoor pond that i haven't cleaned in 6 months (filled with algae and no moving water) and i found a little bullhead that I had accidentally left in there during spring. They will soon outgrow a 10 gallon and will eat anything big enough for them to swallow.