If oil sands process affected water (OSPW) is to be returned to the environment, which will eventually occur, a desire is that it not adversely affect aquatic life. We investigated whether a model fish (rainbow trout) could detect OSPW using its olfactory sense (smell), and whether it would avoid it, thereby limiting any toxicity. We also investigated whether ozonation of OSPW, which lowers the concentration of organic compounds attributed with toxicity (naphthenic acids), would alter any sensory or behavioural responses. We found that OSPW, regardless of ozonation, evoked olfactory neuron responses similar to those expected of natural odorants, suggesting that fish could smell OSPW. In 30 min exposures, olfactory responses to an amino acid were knocked down to a similar degree by OSPW, regardless of ozonation. However, after 7 d exposures, ozonated OSPW had responses no different from control, suggesting that ozonation is a viable treatment for OSPW. In terms of behavioral responses, when fish were given the choice to avoid an introduced plume of OSPW, they did tend to do so, and this was unaffected by ozonation. When fish were given 7 d exposures to OSPW (10% dilution), it altered their response to an amino acid food cue. However, this change was absent in fish that had been exposed to ozonated OSPW, again providing evidence that ozonation is a viable treatment for OSPW. Considered together, our data suggest that fish can smell OSPW, that they may avoid it, and that if they cannot avoid it, that their sensory responses may be adversely effected, unless the OSPW has received some remediation.