Up against capacity‐based approaches to animal ethics, Cora Diamond has put the idea of animals as our fellow creatures. The aim of this article is to explore the implications of this concept for our treatment of fish. Fish have traditionally been placed at the borders or even outside of the moral community, although there is growing evidence that they have perceptual and social capacities comparable to animals that are considered morally significant. Given that a fellow creature's approach is not primarily (...) concerned with capacities, fish may pose a challenge: Can fish be seen as our fellow creatures, and if so, on what grounds? In exploring these questions, we defend Diamond against Jeff McMahan's critique of her account and its implications that the fellow creature‐concept is reducible to either capacities or special relationships and leaves no room for argument‐based moral reform. We suggest that moral attention is key to grasping the moral significance of fish and discuss how scientific research can support such attention. In so doing, we demonstrate how Diamond's approach to animal ethics provides a viable alternative to the dominant animal ethics approaches. Finally, we indicate how this approach can be useful for discussions on industrial fish farming. (shrink)