Fish stocking is a fisheries management tool widely used to augment fish stocks for a variety of purposes including enhancing recreational fishing. Often the measure of success for recreational fish stocking is survival, recruitment and contribution of stocked fish to the fish population or fishery, yet the potential additive effects to the wild fish population or fishery remain unknown. In Australia, fish stocking of recreationally important native freshwater species such as the Murray cod Maccullochella peelii has been occurring for over 30 years since the development of hatchery practices in the 1980s. Despite widespread stocking, the contribution and potential additive effects of stocked fish to Murray cod populations and fisheries has not been investigated. The importance of evaluating native fish stocking in Australia has recently increased due to considerable investment in large-scale fish stocking initiatives for Murray cod in south-eastern Australia (up to a million fish released per waterway). This paper presents an examination of the contribution and additive effects to fish populations (abundance) and fisheries (target preference, catch and satisfaction) from large-scale stocking of Murray cod across six major rivers, and impoundments, exposed to varying degrees of natural recruitment. Our study represents one of the largest native fish stocking evaluations to have occurred in Australia. Results will be of use to biologists, ecologists, policy makers and fisheries managers worldwide in identifying the conditions for additive effects of stocking in the wild, in order to guide the expected considerable future investment in fish stocking.