Koi are among the most cognitively capable ornamental fish, with individual personalities and the ability to recognise their owners — their welfare in garden ponds requires careful management.
Koi welfare is primarily determined by water quality management — the single most common cause of koi suffering and death is poor water quality from inadequate filtration, overfeeding or overcrowding. A koi in clean, well-oxygenated water at appropriate temperature and density is thriving; one in high ammonia conditions is suffering acute gill damage. Beyond water quality, koi are cognitively sophisticated animals that benefit from consistent human interaction, feeding enrichment and appropriate shoaling companions. The longevity of koi — a purchase that may last 30 years — makes welfare management a decades-long commitment.