Post History

There are three options. I will list them from least practical to most, because I don't want people to stop reading halfway through :)

* Parse ssh-agent output with your custom script and re-print it in fish syntax. Always straightforward, but technically makes too many assumptions about the exact output format of SSH agent. Though then again, it's unlikely that a future version will change what SSH agent outputs.
* Use tools like https://github.com/edc/bass which convert bash syntax into fish syntax. May or may not work reliably.
* Use `ssh-agent -c`. This is intended for printing in Csh syntax, should you ever accidentally travel 50 years back in time and actually use C shell. It so happens that the output of SSH agent in Csh mode, though, is also accepted by fish.