One thing to watch on a small pond is the flow through rate. I have two small ponds that flow into my main pond. One is a 1/20th acre forage pond where I raise RES and GSH. Another is a 1/10th sediment pond designed to catch and condition runoff from an agriculture field before it gets into the main pond.
Both ponds I use to raise forage. But the sediment pond, do to it being specifically designed to handle large inflows of water, at times has very high exchange rates of water. This can be very hard on the fish during the times of high exchange rates. At times it might have several full water exchanges in a matter of a day or two. Very stressful on the fish.
The 1/20th acre pond has a more balanced watershed so does not have this stressful condition.
Just something to be aware of if you put a very small pond above the large pond in such a way that lots of water runs through it. I would advise to match the watershed to the pond size if raising fish is the main goal.
My forage pond My sediment pond
