Byobu
From James's Wiki
Put the following in your $HOME/.byobu/.tmux.conf:
nano ~/.byobu/.tmux.conf
nano $HOME/.byobu/.tmux.conf
set -g default-shell /usr/bin/fish
set -g default-command /usr/bin/fish
byobu-enable
byobu-tmux rename-window test
https://www.linuxsecrets.com/3326-byobu-commands
https://askubuntu.com/questions/296377/how-do-i-change-the-default-shell-used-in-byobu-tmux