According to research published in the Nature journal Scientific Reports, fish can remember faces.
(By training archerfish with food pellets as a reward, with a random sequence of 44 faces, scientists were able to teach them to spit at a particular face, with an average accuracy of between 81 and 86 percent. A researcher Cait Newport said "Obviously the first takeaway is that they could do it. They were distinguishing something really complicated. This also shows that the fish have surprisingly good memories. It certainly challenges the whole idea of a fish with a 30-second memory."
Did she really use the word takeaway? I hope she hasn't trained her fish to recognise English.)