Moray eels are not very frequently seen because they are active at night and hide in crevices, but fisherman catch them quite frequently. HK has at least 15 species. Visually similar though not actually a moray eel of the Muraenidae family, is the pike conger (Muraenesox cinereus) which belongs to the family Muraenesocidae, but I have included it at the end for general interest.
White-margined moray (Enchelore schismatorhynchus)
Size: up to 120 cm in length
Areas: around Lamma and Cape d’Aguilar
Rare
Laced Moray / Honeycomb moray (Gymnothorax favagineus)
Size: up to 180 cm in length
Areas: rocky reefs to at least 10m.
Moderately abundant
Large adults can be aggressive.
Highfin moray (Gymnothorax pseudothyrsoideus)
Size: up to 80cm in length
Areas: shallow coral communities, rocky reefs, Pavona decussata (a coral) stands.
Moderately abundant.
Reeve’s moray (Gymnothorax reevesii)
Size: up to 60 cm in length
Areas: shallow coral communities and rocky reefs.
Common. The most numerous species in HK waters.
Scared of divers.
Netted moray (Gymnothorax reticularis)
Size: up to 60 cm in length
Areas: shallow coral communities down to greater depths.
Used in traditional Chinese medicine. It’s liver can be mildly toxic.
Richardson’s moray (Gymnothorax richardsoni)
Size: up to 35 cm in length
Areas: Waglan and Beaufort Islands, Cape d’Aguilar
Rare.
Undulated moray (Gymnothorax undulatus)
Size: up to 150 cm in length
Areas: Port Shelter
Rare.
Reportedly aggressive.
Greyface moray (Siderea thyrsoidea)
Size: up to 66 cm in length
Areas: Sai Kung
Rare.
Pike Conger (Muraenesox cinereus)
see Common Food Fish of HK post from 2014