I second Aquatic Gallery...my definite favorite of the area, but it is pricey.
I stopped by Dolphin Pet Village today and wasn't impressed with their current selection. But as Lordhelmet said, they are moving soon. I don't think they're going to be getting anything new in for awhile, and many of their saltwater tanks were being shut down in preparation of the move...They're moving to a place not too far away, its still on Campbell Ave
from a email i got from them: 1770 W Campbell Avenue, Campbell in Kirkwood Plaza by February 14th. Our new location is between The Right Stuff and Starbuck's.
i know they'll be closed from the 9th to the 14th
Another decent store to check out is King Aquarium on Story Road right near 101 in San Jose. it's hit or miss, but i stop by there every once in a while to see what they have.