In some aquariums you can simply pet fish. Do they like that, or is that unknown?
Science argues a lot about whether fish can be in pain, for example, and therefore indirectly about whether they can feel.
Fish generally have good senses, which inform them about their environment. Just like us, they have senses to see, hear, smell and taste. In addition, there is a line across their entire body that records movements in the water, and they absorb current with their senses. But based on that, it is impossible to say whether a fish can feel anything.
Bacteria also detect harmful substances and flee, but for that reason no one would say that bacteria have an emotional life, partly because they have no nervous system.
Some fish have good brains
The weight of the brain is less than 1% of body weight in most fish species, around 2.3% in humans. Some fish have larger brains, such as the elephant fish, a freshwater fish whose brains make up 3.1% of body weight.
This fish shows many signs of intelligence in aquariums and behaves playfully according to some biologists. It looks like he likes being petted over his stomach. But we must be careful not to attribute human emotions to fish, because they are very far from us in evolutionary terms.