in granada hills, on chatsworth ave & encino avenue there is Fumi's Tropical fisc. not much there, mom & pops store, nice guy Adam at the counter, but sometimes have deals, overall pretty sad
there are couple fish + reptile places near by but dont bother, they used to sell reef stuff but now just fresh water
in canoga park Aquarium City on sherman way and topanga cyn, overpriced fish and coral, guys really pushed to sell stuff by the ahole owner. nearby is vivid aquarium which is mostly coral, nice store, nice people
there used to be much more, but 5-10 stores closed down in the past 5 years
a nice new reef store opened up in Simi Valley on E Los Angeles, called Aquarium Connection. they have a lot of stuff and nice people.
HTH