The spotted estuary smooth-hound or rig (Mustelus lenticulatus) is a houndshark of the family Triakidae, found on the continental shelves and in estuaries around New Zealand. It is closely related to the gummy shark (Mustelus antarcticus) of Australia. Males can grow up to a length of 125 cm, while females can reach a length of 151 cm.It is commercially fished, and is commonly served in fish and chip shops in New Zealand under the name lemonfish.