This chapter argues that even though fishing kills animals and probably causes a lot of suffering, it could still be morally permissible – in the epistemic sense of “could,” understood as “compatible with all we know.” This is because it could be that most fish have net negative lives – that is, they have lives that are, on the whole, bad for those who live them. If so, then the fishing industry is unwittingly engaged in what we, as outsiders to the practice, could understand as systematic mercy killing. After some preliminaries, the author motivates the idea that fish could have net negative lives; then, the author considers and responds to several objections.