The one fish that you really just love, and I know we all love all of our fish but maybe you have a special spot for one in particular :)
Mine is my blue gourami, I've had him now for a little over a year and since he's my oldest fish I really feel attached to him.
This is a photo from when I first got him, he's grown at least an inch, possibly more, since I've had him. Originally he was kept with my king betta, a dragon goby, and African butterfly and I bought him on a whim. He chased and nipped a lot at first but now that he's used to being with bettas and other fish he's very calm, except for the time I tried to add a paradise fish. Never put paradise fish with bettas, or gouramis.