good Luck on this. I know a person/importer that has a store in Moreno Valley, but lives in LA who is very knowledgeable about his fish, but you'd have to buy it from him in order to get the best of his stock. His name is Ajay.
As for stores, they're hard to come by, because they have to have a general knowledge of all the fish in the store and unless it's mbuna or rift lake cichlids that they specialize in, then you'll get general info about them. Good Luck on your search though.
I go to La Habra to a store called Discount Tropical Fish, sometimes the stock the cichlid stock they have is in great condition (usually when they get them on wednesdays) but sometimes you'll end up with bad ones. Just try to get the fish on the day that they receive their shipments.