I picked out fish based on view from side in a tank that was lite. When I placed these fish in a black plastic pond they became very hard to see, I blamed the water. The only fish I was able to really see was a white one. I had picked him from feeder tank because he had a red spot on head ( I had one who looked same from a fair as kid ) Viewing from top against the black background makes it hard to see fish. Can I paint the inside of pond ?