I visited Seafood Paradise (I think that is the name) in Rosemead on Garvey Avenue. It is located close to Wing On, the fresh poultry place and is on the corner of Garvey Ave and a small street. It has a parking lot in the back.
This place has the most variety of live seafood anywhere, and I've been to many Chinese restaurants and markets in L.A. and in Asia.
They have live coral trout from Australia, live eel, live sea turtle, live turtle, live Vietnamese crab, live dungeoness crab, live Alaskan king crab, live Australian coral crab (never seen this before but they are huge, like 20+ pounds), live small abalone, live big abalone from Austalia (huge round ones), live spot prawns, and ton of other live seafood and fish.
The place is pretty clean with a little bit of wet floors around the tanks. The tanks are clean and very clear.
This place is also cheaper than Hong Kong Supermarket. They also have dead fish or fish they just took out of the tank at a discounted price. This is definitely a good place to check out if you like to buy live seafood to cook at home. They have stuff that even restaurants don't offer.