Hi Minde,
Glad to see your new work. I prefer the second one. What is this showering os stones, behavior? I've never seen that before. Are they grabbing a mouthful to get at fungi etc embedded there?
Aquarium photography is indeed a technical challenge for the reasons you mention. Look at some of the work by others here.
Here, for example, is just one set of images by fish photographer, Ron Morse. You'll find more by searching under, "Fish Photo" or Ron Morse.
Here's another one by Brandon Jones.
Thanks for sharing,
asher