I have version 5 currently...
My-MBP-2:~ newbieweb$ perl -v
This is perl 5, version 18, subversion 2 (v5.18.2) built for darwin-thread-multi-2level
(with 2 registered patches, see perl -V for more detail)
Copyright 1987-2013, Larry Wall
and I run El Capitan
I need to instal Perl 6 but be sure in no way that it impacts the current installation of Perl 5, which is used by my system.