Empirical evidence suggests that fishes, as a whole, are emotional and possess intelligence comparable to that of mammals. Furthermore, although data are sparse, recent studies suggest that representatives from the two major “fish” taxa—bony fish (e.g., groupers and cleaner wrasses) and cartilaginous fish (e.g., giant mantas)—may possess self-awareness and a theory of mind. These capacities indicate that a fish could be capable of the emotion of betrayal. Modern, small-scale aquaculture operations present preconditions in which betrayal might be felt by a (...) fish. (shrink)