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.