nvm.fish

function nvm
  bash -c 'source ~/.nvm/nvm.sh; nvm "$@"' nvm $argv

  set -l node_dir "$HOME/.nvm/versions/node"

  switch (echo $argv[1])
    case install
    case use
      set -l node_version (ls $node_dir | grep $argv[2])
      set -l node_version (echo $node_version | cut -d " " -f1)

      set -U fish_user_paths "$node_dir/$node_version/bin"
  end
end

Thanks, this is almost just what I needed (I had to change node_dir to just $HOME/.nvm, and then it worked perfectly)