I should add, I use a relatively inexpensive standard Canon EOS Rebel, almost always with the flash on, stabilization on, and manual focus.
I average about 50 to 100 shots per day, and delete at least 98% of them (sometimes every one).
I use a simple editing program, and find I need
(on most shots) to take down some brightness, because my tank is outside, and uses "no" artificial lighting, only ambient indirect sun.
A recent shot I liked enough to keep, in editing I reduced light by 50%, took color up @ 10% (to match what my eyes seem to perceive), and cropped out superfluous stuff, and erase any obvious spot, (being an outside tank there are often many, I forget to clean off).

I'm sure those with better eyes than mine could utilize any color background, and get good results, but at my level, and equipment, a dark background is easiest for me to get tolerable results.