Yes, white balance is a huge factor when shooting tanks, if your camera lets you adjust the WB then play with that setting with options like cloudy, sunny, etc... or set your own white balance by shooting at off white colors which won't help in overall tank shots but instead might help you achieve the true color of a fish or coral.
I also use a tripod whenever possible for corals, no flash, acrylic tubes to shoot thru water, and yes like you mentioned -high shutter speeds for those speedy fish
happy shooting!