Keith and her colleagues had no idea a mass bleaching event was coming when they first studied the fish at 17 reefs off Japan, the Philippines, Indonesia and Christmas Island.But when one of history's worst global bleaching events struck in 2016, it offered "the perfect opportunity" to study how it affected the fish's behaviour, Keith told AFP.But that number fell to just 10 percent after the bleaching, indicating many "unnecessary attacks," according to the new study in the journal Proceedings of the Royal Society B."Making poor decisions about who to fight, and where to invest their really valuable energy, could be that little bit that tips them over the edge towards actual starvation," said Keith, the study's lead author.It is not clear if the fish will be able to adapt to the changes brought about by coral bleaching quickly enough, the researchers warned."