I have a small 1/4 acre pond directly upstream from the main pond. The pond is about 3 foot deep and feeds directly into the lower pond from an 8 inch culvert. I am thinking that tilapia would be a good choice but I have know idea how you would transfer the fish to the lower pond. I am assumeing that heavy rains would not transfer many fish. Would converting the 8 inch drain into a siphon and running without a screen relocate any fish?

??

How far apart are the two ponds?

It may just be a good idea to manually transfer them to keep somewhat of a control on it and learn a bit. But then again, I really don't know much

Why not just seine them?

Seine is probably your surest option. I have a feeder pond with only a dam separating it from main body of water. I have a 14" diameter pipe discharging water from feeder to main. The feeder pond only has fathead minnows in it. I suspect some go through the pipe as you can almost always catch fish where water falls out of pipe; but also suspect it isn't many. I would anticipate even less with larger fish like your tilapia.

PS: Welcome to the forum. I hope to learn to fly some day. I picked up and dropped off a cardiologist recently at the airport. He showed me his Mooney http://www.mooney.com/index.php plane and we talked about it some. It took him 10 minutes to fly where we normally allow at least 75 minutes to drive and usually takes at least 55 if no slow traffic... Someday...