Greetings Cathy! It seems you enjoy photographing fish. In addition to all the good help you are getting here You might want to take a look at this: http://www.aquatic-photography.com/forum/
I don't get much opportunity to practice shooting fish through glass into water but from what I gather it's rather technically challenging. To get the two shots below I used a shoe mounted on-camera flash and pressed my lens hood flush up against the glass to avoid the light of the flash bouncing off the glass and back through the lens. In the first shot you can see the shadow of the fish down and behind which was produced by the method I described. It's less evident in the second shot, but still visible. I've also noticed that fish don't seem to be very cooperative subjects! Keep at it and you'll have some winning shots before you know it.