Fish Can Recognize Faces, a Surprisingly Human Skill

[Dexter]

http://news.nationalgeographic.com/2015/09/151001-fish-faces-animals-science-oceans/

A school of fish might seem like a sea of identical faces, but at least one species has no problem telling its comrades—and even strangers—apart, new research says. To human eyes, which cannot see ultraviolet light, the Ambon damselfish (Pomacentrus amboinensis), appears yellow with a few spots. But to damselfish, which can see ultraviolet wavelengths, their fellow species sport a complex array of facial patterns that are unique to each individual. "The idea is that these patterns help the fish communicate secretly—without attracting the attention of predators, which, like us, are UV blind," says experiment leader Ulrike Siebeck of the University of Queensland, Australia.

[flowers]

I have a neighbor who feeds the trout in the creek in front of her place. She feeds them cheddar cheese. They only come up to her.

[EC]

Daughter's goldfish (not the brightest bulbs in creation) seem to recognise her and her family. They'll swim towards any family member, but not strangers. 

[truth_seeker]

My wife used to get a handful of goldfish, and walk across the room to the tank with the Oscar, and the fish would literally jump out of the tank, he was so thrilled to get food, or to have a relationship with my lovely wife.

Eventually the uncertainty turned to jealousy, and I got rid of the damn fish. I still have the wife, however.