my FH and koi can recognize me when I come near their tanks, ponds. The FH bit my brothers a lot but they let me pet them, my koi only come up and eat when I'm there, and no one can hand feed them but me!
My smartest fish was a Red Severum. My tank is nearby my computer desk and when I did my work, he would always swim up and down the side of the glass to beg for food. I also think he was trying to see what I was doing. I loved that guy.
My 16'' CKF is really clever he knows all my tricks. Like when i try to feed my catfish that are too shy to come up to the top to eat, he knows were im going to try put the prawn in next(i use a pair of like applier things) He's so cool
My flowerhorn can see me coming a mile away. Hes always poking around his gravel or keeping busy but the moment I walk into the house or room I see him see me and he starts wiggling and splashing for attention (or food really). He even knows when I come in the front door and theres no line of sight and its 30 feet away. Guess he sees the door move a bit from far away.