It is impossible for goldfish to understand their owners. At present, no animal can understand human language. The reason why some animals can act according to the instructions issued by human beings is also the result of conditioned reflex training.

Although goldfish can also be trained by reflex, they rarely give instructions through sound like other mammals.

Goldfish have low IQ and poor memory. People often say that fish's memory is only 7 seconds. Even if it can understand, it will be forgotten if it doesn't respond. So don't fantasize that goldfish can understand people and can only be used as ornamental pets.