I have a above ground pond, its 12' X 8' and 3' deep. I made it out of 4X4's & a pond liner. for the bottom I used left over bricks and covered them with sand then a underlinment for the sides & bottom.
I had 4 koi, 3 goldfish, 7 golden orfe, a black bullhead, a albino channel catfish, a rockbass, 3 longear sunfish, 2 yellow perch, & a green sunfish in it. Its under 2 trees but I was able to have 2 lilly pads in it also.
My pond is 5 years old now and I did not have a problem untill this year, I lost power because of a falty pond heater tripped the braker. So I disconected my water fall (filter) because my hoses were frozen.
I baught a new heater & put it in, then I got real bussy, it worked when I put it in but it must have stopped working soon afterwards. So with no hole in the ice for gas exchange my fish died. I saw something orange right under the ice, so I cut a hole with a axe to find a koi, then I netted out all the dead fish, the only fish left alive were the 3 feeder goldfish. This all took place in December, the company that made the heater replaced it (the store would not take it back) but it took a fue weeks to get the new one.
I have the new heater out there now, I think for next year I will get another one for safety. Also the pond needs checked every day to be sure everything is working.
Mike