I have a tamron 2.8 28-75 lens, little different than the kit lens, but, my suggestion -- shoot in Tv (no flash), bump your iso up to 800, with your shutter speed 1/250 or whatever you can hand hold (or slower if you use a tripod), save it in raw and then use RawShooter essentials to adjust color/white balance/exp compensation...Using RAW gives you lots of options to fix pictures AFTER they have been taken! Good luck!
Another point - shut off all pumps
and another - if you are trying to get a picture of a fish moving around, pick a point to focus on, and when he gets close to that point start snapping away...trying to follow him around the tank will drive you batty!
I am by no means an expert but I have gotten pretty decent pics from trying it this way - the best thing is - it doesnt cost you a thing for the pictures, so shoot away!!
