Located in the heart of Chinatown, the 3-year-old Hung Ming is the size of a supermarket, with four separate floors for pets, pet supplies, fish, and a Chinese video store at the top. Its tanks range in price from $4 to $2,200. At the entrance is a sunken pool displaying the store's specialty -- the robust Japanese koi goldfish, the largest of which weigh more than 5 pounds and sell for up to $400. The main floor of the store has more than 100 large tanks of fish for sale, primarily goldfish of every conceivable size, shape, and color, starting at 12 for $1. The store displays more fish than the Academy of Sciences, which makes it very popular with children. It also sells birds, chinchillas, dogs, cats, cages, pet food, tank decorations, aquarium plants, stones, shells, driftwood, and everything else you need to convert your home into a miniature Sea World. There's a second location at 5000 Mission (586-6891).