Aquarium fish benefit measurably from environmental enrichment, including hiding places, varied substrates, and cognitive challenges. Good tank design promotes natural behavior and reduces stress.
The aquarium industry has been slow to fully incorporate welfare science into best practice guidance. Many commercially sold setups - particularly small, bare, single-fish tanks - fall far short of what fish need for good welfare. The evidence base for fish sentience and stress is now strong enough that bare tank husbandry represents a genuine welfare concern. Simple improvements - adding plants, substrate, and hiding places - have dramatic effects on fish stress indicators. For aquarists, the question should not be 'will this fish survive this setup?' but 'will this fish thrive in this setup?' That shift in framing, from survival to flourishing, drives genuinely welfare-positive aquarium keeping.