what is the smallest heater you can buy cuz i got a 2 gallon hex with opnly a ramshorn snail in it and its non-heated(i dont even have the filter running cuz whats the snail gonna eat then?)so i leave the light on hoping for a little warm up and a little algae for the lil bugger to eat....right now its 55 degrees farenheit and I do not think it should be that cold for him...he still is active and eats the spongy betta bits i put in there(he likes them...but what else can i feed him?)So is there a heater i can get for him or do i need one?