How do zebrafish identify their conspecifics?

Since we are highly social, we are extremely good at recognising other people, in particular faces versus other objects.

                         How many faces can you spot in the image below? (Doolittle; 'The forest has eyes').

Zebrafish are also very good in identifying other fish. They rely on this ability in order to escape from potential predators. They are even able to identify zebrafish strains with different skin pigmentation, and they prefer to swim near familiar zebrafish. This preference is not innate. Fish identify familiar fish if they have been raised with them for the first two weeks of their lives (Engenzen et al.).

What are the salient visual features that fish use to identify familiar zebrafish versus other non familiar fish? What are the brain areas involved in the discrimination between familiar vs non familiar? We are using a combination of virtual assays and two photon imaging to answer this questions (add fish with pigments, bubbles coming out from mouth of fish).