Until recently, those conditions didn’t overly bother too many people. Compared to primates and other lab mammals, fish were perceived as insentient dullards who didn’t require stimulus; as a result, many researchers believed that the logistical challenges of enriching their subjects’ lives outweighed the benefits. But those ways of thinking are being replaced by an appreciation for fishes’ social and cognitive complexity, which raises the question: How do barren environments affect the lives of captive fish? And what might richer ones do for them?