I dunno how big your tank is, but I would have liked to see more of the splash.
In your lemon shot, you have some messy smudges just to the left of the lemon... Patch tool?
I would take the brush tool and sample black from the image and get rid of all those tiny bubbles. It will give the image a cleaner, sharper look. And Ive just seen another (presumed) patch tool smudge at the bottom of the image...
it also looks like you have something red reflecting in your lemon shot on the water surface around the splash... I would also remove that.
Other than that, I like the over all look of the images.