Spoke with jardini owners and read threads like this before. Common consensus is that Jardinis (regular ones anyways, each has its own temperament ) get aggresive as they get bigger, usually when they hit the 10-12 inch mark . Ive had luck with nice sized parrot fish, had a pair with a 12 inch jardini and even managed to lay eggs. They were getting bit though , the parrots were just tough..