Thanks guys.
There's a 140W (35X4) tank light on tank top and Canon Speedlite were used also. All of the light sources were close to front glass, hence, most objects 1ft (or over) away from the front glass become near invisible. Anyway, there are still needs of PS to clean up some minor defects on the background like aeration bubble, algae, feederfishes, or scratches.
The camera used is Canon EOS-20D. For such turning around poses, flash light or fast shutter speed is needed to freeze the motion. In most tank setup, the lighting is never enough (mostly) to support fast shutter speed. It's easier to achieve the effect if use flash gun(s).