Okay, they can’t sit in your lap and purr; but you can still have fun with fish. They can even get tame and friendly. My goldfish used to let me pick them up and put them in the sink when I had to clean their aquarium. I always fed them by hand.
And then there are a lot of funny-looking little fish which I imagine one might get attached to, in time.
There are even fish who get to be friends with cats. How is that possible?