I am going to have to say, my Zebra Danios! These guys are super smart! They know when food is going to be served ( me turning off the filters have them racing to the top of the tank ) None of my other fish ( even Angel ) seem to notice its feeding time but the Danios ALWAYS know! And get this! My 1.5 month old Zebra danio fry do the same thing! As soon as I come up to the tank, they already recognize me and "wait" for their food ( again the filter turning off is the official signal ) I think these guys are great!!!!