Pet fish are among the most numerous but least considered companion animals. The welfare requirements of aquarium fish are frequently misunderstood, leading to preventable suffering for billions of animals.
Pet fish welfare suffers from a combination of public underestimation of fish sentience and widespread misinformation about their needs. Goldfish in small bowls experience chronic ammonia poisoning from their own waste, oxygen deficiency, and temperature fluctuations that cause immune suppression and organ damage. The reality is that goldfish can live over a decade when provided appropriate filtered tanks, comparable to keeping a cat or dog in good conditions. Betta fish in pet shop display containers experience permanent stress from minimal space and stimulation. The scale of pet fish mortality from inadequate care represents an enormous and largely invisible welfare failure. Improving pet fish welfare requires both better pre-purchase education and better regulatory standards for pet shop display conditions.