Oh and for food, I let my tank stay naturally 33-40 throughout the winter, with the exception of during really cold snaps in which I toss in a small aquarium heater set on the lowest setting. I checked mine earlier today and its at 60F which is warmer than I would like, a buddy of mine has a livestock tank heater that only kicks on at 35 and off at 40 so I need to get one of those. Colder you keep it, the less you need to feed. You really dont have to feed at all below 40F, fish can go weeks without eating. But When I do have to feed, I just use normal cheap pond grade goldfish flakes. A tiny pinch every 3-4 days to keep them alive. The more you feed, the more they will poo.. and the more they poo the higher the toxins will get... and the higher the toxins get, well you know the cycle.