Scales from hatchery‐reared, stocked and wild mulloway Argyrosomus japonicus (Temminck and Schlegel) captured in the Georges River, and a library of mulloway scales from coastal New South Wales, were examined for the presence of scale checks. Checks specific for hatchery‐reared fish were present in 100% of recaptured hatchery‐reared mulloway; the origin of which was confirmed by the presence of a chemical mark in the otolith o...