Couldn't this have more to do with the behavior of the reflection mirroring the fish's mental state? Perhaps 50% of the time when one fish shows aggression by f

Couldn't this have more to do with the behavior of the reflection mirroring the fish's mental state? Perhaps 50% of the time when one fish shows aggression by flapping a fin or something the other fish makes a motion that indicates it will move on. That would diffuse the situation and lead to an instance where the fish don't attack each other. In the mirror, the reflection would mimic the aggression and would cause an attack more often. Or perhaps fish know how to size each other up to avoid an attack and when they're the exact same size they attack to figure out who is dominant. Calling it "the enemy within" just seems like we're trying to give the fish a very human-like trait without evidence.