The aquarium hobby maintains hundreds of millions of fish in captivity, with welfare standards that vary enormously from species-appropriate environments to chronically inadequate conditions.
The welfare needs of aquarium fish are genuinely complex and often underestimated. Goldfish kept in bowls experience chronic osmotic stress, oxygen deprivation, and ammonia toxicity. Bettas kept in small containers without enrichment or sight barriers show stereotypic flaring behaviour. Schooling fish kept alone experience social isolation as surely as social mammals. Tropical marine fish, wild-caught with cyanide or physical damage, often die within weeks of import. Yet with appropriate research and investment in species-appropriate systems, fish can be kept in conditions that support positive welfare.