Tropical fish are the most commonly kept pets globally but face widespread welfare challenges from inadequate tank size, water quality, and species-appropriate conditions.
Tropical fish welfare suffers from a combination of their invisibility as individual animals with complex needs and the ease with which they can be purchased by owners with no welfare knowledge. Fish do not show distress signals that humans find compelling, making poor welfare conditions easy to overlook until fish die. The persistence of inadequate tank sizes for betta fish, single-keeping of shoaling species, and cycling-free tank setups reflects a pet industry that prioritises ease of sale over animal welfare. The welfare of fish in well-maintained, appropriately sized, species-appropriate aquaria can be genuinely good: healthy fish with appropriate companions, water quality, and enrichment show natural behaviour, colour, and normal lifespans. The gap between best practice and common practice is wide and requires both better owner education and stronger retail welfare standards.