Since RVM is a large collection of bash scripts and fish is not bash-compatible, users of fish need a wrapper around RVM to make it work properly with that shell. Since RVM just manipulates environment variables, we just need a way to preserve those changes.
Please note that better fish support (although not native) is expected in the future.
Install RVM as you would for use with bash. When
rvm-install command, feel free to ignore the advice under
the "You must now finish the install manually" section.
Download the fish functions from GitHub.
curl -L --create-dirs -o ~/.config/fish/functions/rvm.fish https://raw.github.com/lunks/fish-nuggets/master/functions/rvm.fish
And activate the default Ruby manually in your config.fish file:
echo "rvm default" >> ~/.config/fish/config.fish
Use RVM just as you would in bash or zsh as per the instructions on the website, converting any bashisms to fish as needed.