A Before-After, Control-Impact sampling design was used to measure changes in fish assemblages in intertidal mangroves and saltmarsh prior to and following the closure of commercial fishing in the Botany Bay estuary, New South Wales, Australia. Of commercial species found as juveniles in the wetlands, there was a consistent pattern of decrease in numbers compared to the pre-closure surveys. Other small wetland fish (such as the Gobiidae) were also found to have decreased in numbers, with the exception of the Common Toadfish (Tetractenos hamiltoni Gray and Richardson, 1843) and the Glassfish (Ambassis jacksoniensis Macleay, 1881). Results suggest that the immediate response of an estuarine fishery to commercial fishing closure may be a predator-mediated decline in juvenile fish of both prey and predator species. © 2008, Taylor & Francis Ltd.