For a good fish store, check out Aqua Zoo on El Dorado between I-45 and Highway 3. Might be a bit of a drive from the Pasadena area, but not too bad. It's in a strip center on the west side of El Dorado about a quarter mile from the freeway. It is next to Union Tavern.
They specialize in cichlids, but they have plenty of other fish as well, including a good saltwater selection. They also have some live plants, but their selection is limited. Last time I was there I bought a pair of Endler's.