I finished revamping my outside pond. It now is about 850 gallons, i'm running the pump with water lilies in it to get it started, but there are tadpoles thriving in it now so it seems fine. My biggest problem is that the pond is near a lot of treas (OAK trees), so the leaves give the pond a lot of tannic acid. As you can imagine it means that i would need fish that are both hardy and bright enough to see in the dark water. I now have a small top pond that added the extra 50 gallons, and the pump outputs there, and the small pond splits into two small streams feeding back into the large pond. I was wondering A) if I could heat the upper pond and keep a school of cardinal tetras, which hail from the rios orinoco and negro and should if anything like the tannic acid. My only issue is that although we don't get snow, the pond might skin over once or twice in the winter, so what kind of heating could be needed? I could also bring them in to a vacant kiddie pool in my greenhouse for the winter, but i'd rather leave them where they are. B) what can can I keep in the lower, 800 gallon pond, fish and otherwise. I've considered watersnakes (mainly because I found some cb for $3.00 each, turtles (probably penn cooters or a softshell or the like, but fish have me stumped, as I want to do something really different, and i especially want to avoid plain ol' koi. i am very open, so post your ideas.