loll i hate it when fish do that. now i regret adding the new micro because it seems like its managed to make all my other micros get really scared and jumpy. weird huh.
My grandma's pacu does the same. even if it's just 18", it's really scary watching it smash its face around. It once popped his tank. Good thing i came to check on him. Bastard pacu freaks out even if no one is around.