With more than 30,000 species of fish on the planet, they represent more than half of the vertebrate diversity. Despite the fact that we interact with fish in a myriad of ways (fisheries, aquaculture, scientific research), they attract very little attention from a welfare perspective. Indeed, until recently the common view was that fish are automatons; primitive animals that lack cognitive sophistication.  Over the last 30 years, however, that position has changed dramatically. There is now ample scientific evidence that fish are just as sophisticated as any terrestrial vertebrate and in many cognitive realms they out-perform them. Here I showcase fish intelligence with a view to demonstrating that they are sentient and capable of feeling pain.