You wouldn't go without heat throughout the winter, would you? Lack of a heater is doing the same thing to your fish, except they can't put more clothes on. So, don't skimp on a good heater! The best aquarium heater for your tank is up to you and it's specifics. A small tank doesn't mean that it needs a lower quality heater either, they die all the same, we always recommend keeping a backup for that reason exactly. Our personal favorite is our titanium heater because of its heating capabilities and the fact that it's so hard to break!