Mystery fish

This photo looks like a picture of my camera reflected in the water, which it is, but it is also much more. The little orange line underneath the reflection of the lens is a picture of a fish. This last spring, when it was clear that the cold weather was over and it was time to remove the fish from their fish tank in my living room, I put them all in the lower pool, which is the deepest. One day a few weeks ago, after a heavy rain, I noticed several fish had swum upstream into the middle pool. This wasn't too surprising, because when there is a lot of water in the pond, the levels in the two pools are close and the waterfall between them isn't serious. The fish eventually moved back to the lower pool. Then, two weeks ago, I saw a flash of orange in the upper pool. I didn't believe it at first, but then I got a better look at the mystery fish and took a photograph. I have no idea how it got there, because the trip from the middle pool to the upper pool involves jumping up an inch high waterfall and crossing a foot long area where the water is only just covering the rock - Did it really swim upstream like a salmon? Soon I will post pictures of the obstacles to reaching the upper pool from the lower pool, and you will see how just amazing that feat would be.