_Heaters/Coolers:_The only way you can get away with not having some kind of heater is if your tank is in a location that is consistently at the desired temp.
_Heaters/Coolers:_The only way you can get away with not having some kind of heater is if your tank is in a location that is consistently at the desired temp. Spoiler alert: most of the time, it's not. Most tropical plants and fish need temps between 75 and 80F. Some species, like axolotls, need colder water. It's usually just easier to get a heater (or a cooler) - many are preset or easy to set to a particular temp.