Aquarium fish are among the most commonly kept pets globally but are frequently housed in conditions that fail to meet their basic needs. Overcrowding, inappropriate tank size, and poor water quality are widespread welfare problems.
Fish kept in aquariums are entirely dependent on their owners for all aspects of their environment, yet many are kept in conditions that cause chronic stress and shortened lifespans. The evidence that fish can experience stress and potentially pain makes inadequate aquarium conditions an ethical concern. Common mistakes including insufficient tank size, failure to cycle tanks, incompatible species mixing, and overfeeding can be avoided through research before purchase. The impulse buy of fairground goldfish or pet shop fish without prior research leads to preventable suffering for millions of fish annually.