Betta fish are among the most widely sold aquarium fish globally, kept in conditions that welfare science now recognises as severely inadequate for their complex behavioural needs.
Bettas kept in unfiltered cups or small bowls suffer from ammonia accumulation, temperature fluctuation and severe restriction of natural behaviour including territory exploration, courtship display and fin-flaring. These are cognitively complex fish — studies show bettas recognise their own reflection and show consistent individual personality traits. The welfare standard of individual cup isolation in retail is now widely condemned by fish welfare scientists. Minimum tank size recommendations have increased substantially as welfare understanding has advanced.