As for picture taking i have a Nikon D40 with reg lens and a extend lens 55x200mm
what i do is take far away shots with room lights off and only my tank light on with the flash off but you have to be very steady, most turn out blurry. close up shots i use the same technique but i use the flash on and get real close with the zoom or i switch out to my lower 18x55mm lens get right up to the tank and capture at an angle normally aiming down at the fish yields best results..