Photo help

[spoot]

-Turn off the room lights if you are trying for shots of the inhabitants of the tank.
-Clean glass thouroughly inside and outside of the tank.
-Tripod is best, but not always useful for fast moving fish.
-For fast moving fish, an external flash may be needed to have enough light for faster shutter speeds.
-For best results, shoot perpendicular to tank, as the tank's glass will distort the picture and possible mess with the auto focus.

I agree with Cathering though, best to show us a sample so we can see what needs fixing.