Australian researchers have found that fish operate a strict pecking order that punishes queue jumpers; fear of being shunned by the group leads to some fish starving themselves to avoid confrontations with those higher up the hierarchy. James Cook University researcher Marian Wong made the discovery by studying the behaviour of gobies living on reefs around Lizard Island on the northern Great Barrier Reef. Amongst this species, only the top male and female mate. All of the other females have to wait their turn in a queue which is based on their size. Each fish has a size difference of about 5% from the one above and the one below it in the pecking order. But if the difference in size decreases below this threshold the smaller fish tries to jump the queue and, responding to the challenge, the superior fish will try to drive the upstart from the group. Explusion in this way would mean almost certain death so, Dr Wong has found, the fish deliberately stay slimer than their seniors to avoid rocking the boat!