Don - Great pic of dinner critters -- really great pic! I've eaten most of those at one time or another.
Normally I don't tweak snapshots, kind of defeats a snapshot as a snapshot, but aquariums made of glass might be an exception -- they are essentially colored lens filters. Aquarium glass has color, usually either greenish or blueish that our brain corrects for, but a camera (digital or film) does not. (Acrylic aquariums are virtually colorless, pix of fish in them don't need tweaking.) I suspect the grill with holes in your photo is supposed to be white. If you correct for that you will also remove the blue-greenish tint from dinner, umm, I mean the fish.
I snipped a piece of your pic, resized, subjected it to PSE auto cast remove tool. I think it evaluated the white grill as gray, but it gives you an idea of how effective a colored lens filter aquarium glass is.
Unfortunately, when the aquarium is not the only thing in the pic you are stuck having to correct for color cast only in the area where the aquarium glass is, else you bias the color in the rest of image.
Did I mention how much I love black & white photography?