My pair of tiger oscars attack me any chance they get. They beg, and when I go over to feed them, they almost jump out of the tank (they get all the way out of the water) and they go for the fingers. They like to bite and hang.
And if I'm not paying attention to them, they swim up the the surface and barrel roll, flipping a bunch of water out of the tank all over my homework (my hood's broken and it didn't take them long to figure it out)