June 23, 2016 6:02 AM EDT

Even some vegetarians opposed to animal cruelty say it’s fine to eat fish, citing their lower brain capacity. But in his new book, What a Fish Knows: The Inner Lives of Our Underwater Cousins, Jonathan Balcombe argues that there is a huge moral distinction “between a cod and a cucumber.” To illustrate his point, Balcombe cites several studies about how fish live. Among the findings (some of which are disputed): rainbow trout can probably feel pain; carp can learn to avoid bait for up to three years after getting caught and released; cichlids engage in play; frillfin gobies can memorize and recall the topography of a tide pool 40 days later; and orange-dotted tuskfish can use tools to uncover and open buried clams. “Fishes are not merely alive–they have lives,” writes Balcombe, who also serves as director of animal sentience at the Humane Society Institute for Science and Policy. Knowing that, he concludes, “it is time for a paradigm shift in how we think about and treat [them].”


This appears in the July 04, 2016 issue of TIME.

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