Cam, a couple of thoughts.

A spring is actually an aquifer starting with ground water. As long as the water table is higher than the outlet, it will flow. However, in droughts, the water table drops and the spring flows backwards to replenish the lower parts of the aquifer. In the Spring time, trees start putting on leaves as the sap rises and calls for ground water. I have one very small pond that gets drained every summer as the water table drops and the head pressure changes or reverses. In my drought ridden area of North Texas, that little sucker has been mostly dry for 3+ years. So a spring in a pond can drain back into the surrounding area.

I'm not sure about smart/dumb fish. It appears that a lot are smarter than me, especially, 2 to 3+ year old cats. I do know that some fish are more aggressive than others and grow larger and quicker. Put 100 fingerling bass in a large tub. In a week, you will find that you no longer have 100. They've eaten each other. I've watched this several times when I've seen two 1.5 or so inch long bass next to each other. Then, one of them has the tail of the other sticking out of its mouth. The predatory one may or may not survive it's gluttony. The survivors are called jumpers or hog outs and will outgrow their siblings. According to one University study, Auburn I think, found that some fish seem to be genetically inclined to avoid hooks. Smart? Maybe and maybe not. But I do know that my larger cats will seldom bite or even eat much fish food when I use a red and white bobber. Florida bass are notorious for getting larger than natives but are much harder to catch. Smarter, bigger brains or genetically inclined? Heck, I don't know but genetics seem to be the answer.

Successful ponds are all about the environment we supply and food. Food is the absolutely essential balance between predators and prey. The environment is mostly about water quality and that has to be monitored.

It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP