Ah, another participant! I believe you may have left out your social security in the EXIF data Pat
Luckily, your shot I can view in a much large format via Flickr.
Very good selection on your f/stop. Any more stopped down and you would have gotten too much definition on the rear elements. With that being said, I'm sure you know that I have to talk about the background discus.
Aquarium photography is very difficult because you almost always seem to catch a distracting element in the rest of the tank that degrades the shot. This is difficult to deal with, but not impossible. Zooming in of course will get you more of your subject in the frame, and less of the rest. However, with the positioning of the other discus, this would have been just as distracting with the rear elements even if zoomed in. My advice? You will have to follow the discus around and try to isolate it in the tank somehow. It is difficult, but I have done it successfully by sheer persistance.
Your exposure is great considering the flash is right over the tank. Are you using any type of diffuser?
Larger size analyzing shows that your focus is right around the forehead eye area. Remember to always use the eye as the point of focus whenever possible. If you have enough time, try to manually focus on the eye for that crystal clear eye
Other than that, I see no problem with this shot. I do love seeing isolation in these type of shots, unless the surrounding cast is doing something interesting, like lining up in a certain way, or attacking a cube of worms, or sizing each other up for battle, lol.
You are doing excellent though and I am really proud of you Pat