Goldfish are not as intelligent as other kinds of pets but naturally behave in cute ways. Goldfish love to interact with other goldfish and prefer to live in groups. They also enjoy playing all day and even taking naps from time to time.
When goldfish sleep at night, they do not close their eyes because they do not have eyelids. Goldfish often swim up to the glass of their aquarium to meet people. Most likely, this is because they think food is on the way. There are studies that suggest that a goldfish's memories can last up to three months.