Research into fish cognition consistently reveals greater complexity than assumed, with tool use, social learning, individual recognition and play behavior documented across multiple species.
Fish intelligence research has repeatedly confounded expectations based on the assumption that simple brain structure means simple minds. Tool use, social cognition, individual recognition, play behavior and potentially self-awareness have all been documented in different fish species. These findings have implications for welfare: more cognitively complex animals likely have richer inner lives and greater capacity for suffering. The scale of fish use in commercial fisheries and aquaculture — trillions of individual animals annually — makes these welfare implications enormous. Treating fish as simple stimulus-response machines rather than cognitive beings with individual perspectives is increasingly scientifically indefensible.