Hi there, I just bought my first Beta (Puppy) a month ago. it's starting to cool down in Canada and I'm wondering about a heater. I have him in a large glass vase with a square top....is there a heater that hooks over the side? Or maybe one you set the bowl on top of? He seems happy, although he's a little less aggressive lately. he used to get really excited at feeding time and even takes pellets out of my hand! he's still eating, but is slowing just a little. Should I be worried? and is my gut right that I might need a heater? Thanks!