Fish kept as companions must be kept in aquariums that maintain species-appropriate water quality, lighting, and temperature and provide complex environments to explore and hide. Fish kept as companions should be kept in species-appropriate social environments and be fed species- appropriate diets.

SPCA opposes the keeping of fish in aquariums that are not aerated, filtered, or enriched, such as fishbowls, and advocates that keeping fish in these environments is banned.

Keeping fish in these environments can lead to poor welfare due to increased environmental and stress-induced disease and behavioural abnormalities.

SPCA opposes the wild capture of marine and tropical fish to be kept as companion animals due to the methods of capturing these animals and the high mortality post-capture.

The mortality rate for wild-caught marine and tropical fish post-capture is predominantly due to transportation and physical injury, stress, water quality changes, water temperature and exposure to chemicals used as prophylactic treatments for disease control.