Home aquarium fish welfare is frequently poor due to inadequate tank sizes, inappropriate water conditions, and insufficient understanding of species-specific needs.
The welfare of pet fish is among the most poorly understood in companion animals. Millions of fish are kept in tanks so small that they cannot express normal movement, in water conditions causing chronic physiological stress, with inappropriate companions or in inappropriate isolation. Fish often suffer for extended periods before dying - ammonia poisoning from inadequate filtration causes gill burns and pain. The casual nature of fish keeping - fish purchased as beginner pets or impulse buys - means the level of research and investment applied to their care is often grossly inadequate for their welfare needs.