Ok, I'm bored, so here's a tip
When shooting without flash, it's best to shoot with the lens as parellel to the tank as possible. Light defracts more and more through glass/acrylic with increasing angles; shooting at extreme angels usually results in underexposure (lack of contrast, saturation, and fine details), not to mention significantly altering perception/proportions.
When shooting with on-camera flash, you have little choice by to shoot at an angle to avoid flash bounce. If your camera accepts external flash (through a hotshoe or flash sync terminal), it can dramatically improve your results. Align your camera parallel to the subject/glass, and handhold or mount the external flash at an angle.
When shooting without flash, it's best to shoot with the lens as parellel to the tank as possible. Light defracts more and more through glass/acrylic with increasing angles; shooting at extreme angels usually results in underexposure (lack of contrast, saturation, and fine details), not to mention significantly altering perception/proportions.
When shooting with on-camera flash, you have little choice by to shoot at an angle to avoid flash bounce. If your camera accepts external flash (through a hotshoe or flash sync terminal), it can dramatically improve your results. Align your camera parallel to the subject/glass, and handhold or mount the external flash at an angle.