went there last year myself...
believe it or not
when i came back from the trip i brought back a couple of live plants (freshwater)...
one of my friends that lives in HK said he knew people brought the large imperator angel fish on the plane back home... don't know if its true or not
but i brought back some live plants and they were x-rayed when they past the security check point so corals might not be that out of hand
