Fish kept as companions are among the most neglected animals in terms of welfare understanding. Scientific evidence shows fish are sentient beings with complex needs that most aquarium setups fail to meet.
The widespread treatment of fish as living decorations rather than sentient animals reflects a failure to apply scientific evidence about fish cognition and welfare to common husbandry practices. Small glass bowls, inadequate filtration, incorrect water chemistry, and inappropriate social conditions cause chronic stress and shortened lives in billions of companion fish annually. The welfare science is clear: fish have nociceptors, show avoidance learning after painful stimuli, and exhibit behavioral indicators of positive and negative states. Applying this knowledge requires matching tank size, water conditions, and social grouping to species-specific natural history rather than marketing claims on pet store packaging.