Dark fish

Today, something that I have long suspected was confirmed. There isn't A fish in my upper pool, there are three! The reason I wasn't sure before was that two of them are dark colored and aren't easy to see against the bottom. Which is why it's really weird ... I didn't buy any dark colored fish from Petco, exactly because they don't show up against the muck on the bottom. So where did they come from? They could have been sucked up by the pump when they were just eggs and dumped out into the upper pool, but they are BIG, as big as the fish I've had for a year. Or, they could have hitch-hiked in with the plants as eggs, but they are appear to be normal goldfish, so what would they be doing living in a pond in New Hampshire? And again, they are too big to be this years crop, unless they were from the very early spring, which rules out the hitch-hiker theory. I don't really recognize the orange color fish they live with either, although in truth all goldfish kinda look alike. At least now I'm not worried that the fish in the top pool is lonely (they seem to be very school oriented) but it's a wonder. Maybe they are misdirected alien sleepers waiting to take over the earth.