I would have liked to see the fish sharper. When there is a glass between the subjeckt and the camera, Manual focus and high apparture is nessesary. Also good to have a tripod.
Photographing fish in a tank can be hard. If you know the thickness of the glass in mm, you can back focus twice the distance in mm to get the subject in focus. I once had to catalogue all the fish in a local pet shop. Using a remote flash from the top of the tank realy provides the best illumination.