As ornamental fish, koi are generally believed to be spiritual and can know, like and communicate emotionally with their owners. However, there is no clear rule as to when koi fish become spiritual.
Some breeders believe that when koi grow to about 20cm, their cognition and behavior have changed. May begin to show attention and responsiveness to its owner, and is seen as spiritual. However, this is only a personal subjective judgment and summary of experience, and does not fully represent the cognitive ability and behavioral performance of koi. Therefore, the spiritual cognition of koi should be observed and studied with an objective and scientific attitude and method.
