I wouldn't judge that as aggression. Look at the fish, it is basically saying "leave me alone!". It is trying to get away, not attack. It is acting cornered, not aggressive.
I've seen a bunch of videos where people do the same thing with Piranhas. But with the Piranhas, people take them out of the water and force a finger into their mouth and say "look what this Piranha can do! look how mean they are!".