The potential for spills or leaks of untreated hypersaline chemically complex flowback-produced waters into surface waters is of concern, both due to the direct toxicity to organisms and perturbations to the ecosystem even at considerable dilutions (>100-fold). Direct toxicity assessment (DTA) was utilised using Daphnia carinata to investigate the toxicity of a hypersaline shale gas produced water sample from the Beetaloo Sub-basin, Northern Territory, Australia. It was acutely toxic at 2% v/v while a matching v/v salinity control had slight acute toxicity. Reproduction was stimulated during chronic exposure at 0.25 – 1% v/v shale gas water compared to the control and generally coincided with increased size of individuals. Combined metabolomic and lipidomic analysis resulted in 103 significantly altered compounds across 5 select treatments, 74 of which were lipids. Metabolic pathway changes relative to the control were more impacted in individuals exposed to shale gas water compared to matching v/v salinity control. This confirms contribution of other chemical constituents to overall toxicity not just the hypersalinity component. Sub-lethal exposures via potential spills or leaks of chemically complex shale gas produced waters to freshwater invertebrates could reduce overall fitness, thus having lasting impacts at a species and interspecies level in freshwater environments.