Three stripes make clownfish aggressive. This suggests they are able to count the number of bars in order to identify the type of intruder.
It is said that anemonefish get their third and final stripe when they are big enough. The respective alpha fish therefore uses harsh methods to maintain its status. For example, by chasing away other colony members. The study is a sobering reminder to protect the fragile coral reefs where fish like the anem onefish live, lead author Kina Hayashi said.