Oh thats a difficult one to answer. Of the fish i can see all the time my jardini arowana is probably my favourite though i also love my 3 shovelnose catfish. When it comes to feeding time my sabretooth tetras are fantastic, the way they hit the frozen fish as i drop them in and work their jaws to swallow the fish which are half their body length is just amazing.
Then there are the nocturnal fish that i rarely see like my leiarius pictus, bichirs and dwarf girraffe cats which always give me a little buzz when they unexpectedly appear at feeding time to snatch a mouthful of food.