Successful spawning and recruitment of native freshwater fish species is dependent upon environmental conditions that optimise larval survival and growth. These conditions seldom occur in regulated rivers where altered flows are often unsuitable for native fish spawning and or recruitment. Environmental water actions target species recovery by restoring key features of the hydrograph. We investigated larval fish abundance in a lowland section of the Murrumbidgee River during a targeted environmental watering event between September and December 2012. The event aimed to increase the inundation of spawning sites for a nesting species (e.g. Murray cod). Estimates of demographic structure indicated that cod (Maccullochella spp.) spawning occurred from mid-October through to early December, coinciding with environmental water delivery. Significant differences in cod abundance occurred among the three in-channel sampling sites. Larval cod abundance was significantly associated with abiotic variables such as electrical conductivity, water temperature, turbidity, nutrients, and river height. Importantly, microcrustacea abundance peaked during the environmental watering event, providing a food source for larvae. Collectively, these results indicate that the timing of environmental water delivery was sufficient to enable spawning, and that the associated ecosystem responses were conducive to the survival and growth of larval fish.