Fresh water inflows have long been linked to secondary productivity and fishery catch rates in estuaries. While inputs of allochthonous nutrients are purported to increase primary production and subsequently secondary production, the role of allochthonous carbon in this process is still debated. We performed an experimental mesocosm study where the effects of varying levels of dissolved organic carbon (DOC) additions to the diet of juvenile Australian bass (Maquaria novemeculata) were investigated. Artemia sp. nauplii were on grown in mesocosms with additional concentrations of either 5mg or 10mg of DOC for 2 days. DOC additions were administered through a naturally derived allochthonous leachate (.45µm filtered, from Casuarina glauca and Eucalyptus sp.). Artemia sp., bio encapsulating the carbon leachate as well as subsequent bacterial communities, were then fed to juvenile bass in their treatment microcosms over 42 days. Juvenile fish in the 5mg treatment exhibited no statistical difference for weight, standard length, fork length or total length compared to the control. However, fish in the 10 mg treatment had significant increases in all length parameters after 28 days as compared to other treatments and were significantly different in weight by 42 days. Changes in delta-13C of fish in the 10mg treatment indicated assimilation of terrestrially derived material and changes in delta-15N indicated nauplii in this treatment were of higher nutritional quality than other treatments. We conclude that additions of allochthonous material to estuaries by inflows may have the ability to influence the growth rates, and potentially recruitment, of juvenile Australian bass. This may have implications for inflow and fisheries management when considering the timing of environmental releases.