Question 1) I know I should have a lot of patience with these guys, but they are scared of everything and will always hide when I go near the pond. They're extremely smart! They learned the sound of the patio door and will hide as soon as we open, but rome around once we close (I have a clear view from the bedroom from above). I've had 4 rats die in the pond (try to go for food, can't get back out = dead). I've been good that I always scoop them out right away and the parasites/diseases dont leach into the pool. Fish were definitely spooked. Is there any "quick" (probably not) way of getting them comfortable again? 2) I had my Hikari and Bully jump out of the pond today which was quite alarming. It wasn't as if they jumped onto the rocks (if the water was higher they could, which is why I leave it as low as it is from the top), more like a dolphin jump then back in. Is this normal? Is it just Koi for "hey we missed you!" - lol just kidding. 3) I'm thinking of a water heater for the winter or simply placing a piece of plywood to cover 3/4 of the pond. I'm in Ontario, Canada and temperatures have already dipped under 10C//50F so I stopped feeding them as of last night. Would the heater/plywood suffice? The pond is about 2.5-3 feet deep. Thanks, Jimmy.