pond setup

i move in this house a yr ago and it had a pump all it had was a filter and two ponds conected, we added another one and a waterfall that goes to two of them, we added a uv pump. i was just wondering what else do we need for it to stay healthy, last summer we lost three of the fish that came with the house when we had 100 and something weather, we know it was because it was hot and we need to circulated and air rate it. so we left the waterfall on. but we dont want to do that this year it cost to much to keep it running. also i was wonder we bought 7 more and we still had two left from the ones that can with the house, the all live thru the winter but when all the ice melted the started dieing off now we have the two that came with the house and one of the little ones we bought, does any one know what went wrong, what did we no do.

Just read your post. Day late and a dollar short but what the heck. Here's some things to think about. Over heating and poisoning. Over heating is self explanatory. Toxic water, that can come from different sources. Lack of circulation, over feeding or bad food maybe and poison are a few. Poison meaning something got into the water somehow. Weed killer, bug spray, bad food, whatever. Just some thoughts, hope they help.