Starting from here on, You have to pay the cost to be the boss. These equipment can be costly and might injure your wallet severely. The Objective, (it's very simple):
Taking picture of creatures inside the aquarium, with good exposure, no glare, and sharp. The Equipment.
1 Tripod (you can find some cheap and sturdy ones for $20)
1 Digital Camera that you can adjust the shutter speed and aperture manually.
1 Off Camera Flash ( this is just the flash that you normally mount on top of the camera(anywhere from $10-$450)
1 Stand for the flash (you can hand hold this, around $40)
1 PC sync cord (to connect the camera to the flash, no more than $10) Getting Sharp Pictures:
The tripod should do the trick. Set up your camera and point the lens around your fish's favourite spot!! and bribe your fish with food to pose for you. Lighting Setup:
This is where we take care of glare problems.
The flash can be set up either to the left or to the right of the camera, just make sure the flash ray is not reflecting and bouncing off the aquarium glass into the camera. Tilt the camera at an angle into the aquarium.
Pointing your flash straight onto the aquarium and tilting your camera at an angle keeps the glare away as well. Exposure
There are two factors that effects the exposure, the shutter speed and the aperture. the flash is controlled by the aperture and the ambient light is controlled by the shutter speed.
1. for close up - set your aperture at around f/5.6
for Whole Aquarium shot - set your aperture at f/8
2. try to get a good exposure by playing around with the shutter speed, and keeping your aperture the same as above. if your shutter speed exposure is only at 1/10-1/30, you need to bring in an extra light (like a table lamp) for the overall scene, because fishes move and you need to be at least at 1/50-1/60 depending on how fast your fish swim or move.
3. when you get those two tuned, get a good exposure on the flash. if it's too bright then turn it down if it's too dark then crank it up.
4. when you tweak the aperture, you have to re-tune and match the flash and vice versa.
This is still work in progress, i will add pictures and keep improving this. Good Luck.