Home aquarium fish are among the most commonly kept pets but receive less welfare attention than dogs and cats, despite experiencing stress and suffering under inappropriate conditions.
Aquarium fish experience stress responses including cortisol elevation, immune suppression, and behavioral changes under poor housing conditions. Overcrowded tanks with inadequate filtration expose fish to chronic ammonia and nitrite poisoning. Temperature and pH outside optimal ranges cause physiological stress and disease susceptibility. Wild-caught marine fish experience capture trauma, transport mortality, and adjustment to captive conditions that impose significant welfare costs before they even reach aquarium owners. Responsible aquarium keeping that matches tank size and water conditions to species requirements, sources captive-bred fish where possible, and provides environmental enrichment including hiding structures and species-appropriate social groupings provides genuinely better welfare outcomes.