A nice guide on ArchWiki. A configuration for Bash:

.bashrc

# Drop in to fish shell if:
#   1. Parent shell is not fish
#   2. Not executing a bash command, e.g. 'bash -c'
if [[ $(ps --no-header --pid=$PPID --format=comm) != "fish" && -z ${BASH_EXECUTION_STRING} && ${SHLVL} == 1 ]]
then
	shopt -q login_shell && LOGIN_OPTION='--login' || LOGIN_OPTION=''
	exec fish $LOGIN_OPTION
fi

Commentary on the fish shell by Julia initially, more recently, and on modern terminal setups.

A checklist for new users (like me) to configure Fish:

• Run fish_config to configure via a web browser.

Also apparently dotfiles are a thing: https://dotfiles.github.io/

Also Bass might be interesting: https://github.com/edc/bass

set -U fish_greeting

• VSCode's remote SSH extension (as of 2025-02-10) does not play well with a default Fish shell on the remote side. Either modify the way .bashrc checks whether to activate the Fish shell, or on the client side VSCode set remote.SSH.useLocalServer = false in the workspace configuration.
• Installing fish on old OpenSUSE might be a bit difficult (fish:v2.7.1).
  • First to resolve is the automated web browser opening requirement, which can be disabled by commenting out the webbrowser.open line in /usr/share/fish/tools/web_config/webconfig.py.
  • Extract the localhost path stored in /root/.cache/fish/web_config-*.html, then forward the default :8000 port and use the web config.
  • Prompt may fail when using the web config. Insert it manually at .config/fish/functions/fish_prompt.fish. A simple I like, using the interactive prompt as base and substituting the $PWD for (prompt_pwd)

.config/fish/functions/fish_prompt.fish

function fish_prompt --description 'Informative prompt'
    #Save the return status of the previous command
    set -l last_pipestatus $pipestatus
    set -lx __fish_last_status $status # Export for __fish_print_pipestatus.
 
    if functions -q fish_is_root_user; and fish_is_root_user
        printf '%s@%s %s%s%s# ' $USER (prompt_hostname) (set -q fish_color_cwd_root
                                                         and set_color $fish_color_cwd_root
                                                         or set_color $fish_color_cwd) \
            (prompt_pwd) (set_color normal)
    else
        set -l status_color (set_color $fish_color_status)
        set -l statusb_color (set_color --bold $fish_color_status)
        #set -l pipestatus_string (__fish_print_pipestatus "[" "]" "|" "$status_color" "$statusb_color" $last_pipestatus)
 
        printf '[%s] %s%s@%s %s%s %s \n> ' \
            (date "+%H:%M:%S") \
            (set_color brred) $USER (prompt_hostname) \
            (set_color $fish_color_cwd) (prompt_pwd) \
            (set_color normal)
    end
end