How to add exports to fish like in .bashrc?

You can put the user-specific fish configuration, including set directives, in ~/.config/fish/config.fish. The contents should look more or less like that

set -x PERL5LIB /home/iaco/workspace/perl:/home/iaco/devtools

More information can be found in the documentation.

Use universal variables introduced in fish 2.0.0. -x means exported, and -U means that it's declared for every fish session. You can also use the long options --export and --universal.

set -xU PERL5LIB /home/iaco/workspace/perl:/home/iaco/devtools

Please note that PATH variable is a bit of a special case. While PATH can be universally changed, this will affect your current PATH variable (which may be a bit of a problem if an extra path will be introduced by an operating system). For PATH variable, use fish_user_paths variable (which only adds paths) instead. The variable is an array, which means you don't have to put : characters.

set -U fish_user_paths /home/iaco/workspace/perl/share/bin /home/iaco/bin $fish_user_paths