This image exists on the internet in two ways. I could not decide which crop I liked best. This version leaves out the more noticeable streaks on the glass and creates a frame around the fish.
About the composition. It was before the aquarium lights had turned on, and I wanted to check on the goldfish and the snail. The fish always seem skittish otherwise. After I scraped off more algae, I wanted to get in as much camera time as possible. They are a challenge to capture.
Under the circumstances, it was hard enough to see the subject much less find them in the viewer. I certainly did not expect that it was possible to even get a shot. To my delight, this has resolved the problem of reflected light I usually have with goldfish.