A person more experienced in these things, suggested moving the camera much closer to the aquarium and setting it on a stable surface. He then recommended using the manual setting to adjust to the specific fish you wish to photograph. I have so much more to learn along those lines.

Are you using a manual focus? Your camera doesn't seem to be focusing on the front glass - a common problem with autofocus. You seem to be effectively overcoming that!

I would like to get a camera with a faster shutter speed. That will not happen for some years. A way of somewhat dealing with that is to put your fish in a small tank, such as a 2.5-gallon or smaller. A piece of glass is cut to fit inside that tank. It is gently moved forward and set in the gravel, so the subject can't swim away and especially can't swim out of focus.

That guy - Karl Doering - is giving a workshop on photography in Northern Indiana at a show the last weekend in February. He will also be showing video of his killies and angelfish. If anyone on this list is in the area and is interested (it is a freebie, except for transportation) details can be sent off-list or as a further comment here.

Indiana is a long way from the Left Coast where you live. If you check the sites of local aquarium clubs and specialty groups, you may find someone doing a similar presentation sometime this year.