There is already a "fish" shell.
diff -ur bsd-games-2.17.orig/fish/Makefrag bsd-games-2.17/fish/Makefrag
--- bsd-games-2.17.orig/fish/Makefrag	1970-01-01 07:00:01.000000000 +0700
+++ bsd-games-2.17/fish/Makefrag	2020-08-06 19:18:43.204492847 +0700
@@ -31,7 +31,7 @@
 fish_all:	fish/fish fish/fish.instr fish/fish.6

 fish_install:	fish_all
-	$(INSTALL_BINARY) fish/fish $(INSTALL_PREFIX)$(GAMESDIR)/fish
+	$(INSTALL_BINARY) fish/fish $(INSTALL_PREFIX)$(GAMESDIR)/fish-game
	$(HIDE_GAME) fish
	$(INSTALL_DATA) fish/fish.instr $(INSTALL_PREFIX)$(FISH_INSTRFILE)
	$(INSTALL_MANUAL) fish/fish.6
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<div class='path'>path: <a href='/guix/log/?id=6c77b5a9f7856d44e7405ff3fd6458629004d555'>root</a>/<a href='/guix/log/gnu?id=6c77b5a9f7856d44e7405ff3fd6458629004d555'>gnu</a>/<a href='/guix/log/gnu/installer?id=6c77b5a9f7856d44e7405ff3fd6458629004d555'>installer</a>/<a href='/guix/log/gnu/installer/keymap.scm?id=6c77b5a9f7856d44e7405ff3fd6458629004d555'>keymap.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/installer/keymap.scm?id=6c77b5a9f7856d44e7405ff3fd6458629004d555&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-01-17 14:04:25 +0100'>2019-01-17</span></td><td><a href='/guix/commit/gnu/installer/keymap.scm?id=479414e1c9e13ddce9e0c8741eb9f50dff62e333'>installer: keymap: Do not fail on non-kmscon terminals.</a><span class='msg-avail'>...<span class='msg-tooltip'>kmscon-update-keymap fails on non kmscon terminals because KEYMAP_UPDATE
environment variable is not defined. As it is convenient to test the installer
on a regular terminal, do nothing if KEYMAP_UPDATE is missing.

* gnu/installer/keymap.scm (kmscon-update-keymap): Do nothing if KEYMAP_UPDATE
is not defined.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2019-01-17 14:04:23 +0100'>2019-01-17</span></td><td><a href='/guix/commit/gnu/installer/keymap.scm?id=c088b2e47f6675199f1ef545df7d04d4532e64e3'>installer: Do not ask for keyboard model.</a><span class='msg-avail'>...<span class='msg-tooltip'>Suppose that the keyboard model is "pc105".

* gnu/installer.scm (apply-keymap): Remove model ...
* gnu/installer/newt/keymap.scm (run-keymap-page): passed here.
(run-model-page): remove procedure
* gnu/installer/record.scm (installer): Edit keymap-page prototype in comment.
* gnu/installer/keymap.scm (default-keyboard-model): New exported parameter.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2019-01-17 14:04:20 +0100'>2019-01-17</span></td><td><a href='/guix/commit/gnu/installer/keymap.scm?id=d0f3a672dcbdfefd3556b6a21985ff0e35eed3be'>gnu: Add graphical installer support.</a><span class='msg-avail'>...<span class='msg-tooltip'>* configure.ac: Require that guile-newt is available.
* gnu/installer.scm: New file.
* gnu/installer/aux-files/logo.txt: New file.
* gnu/installer/build-installer.scm: New file.
* gnu/installer/connman.scm: New file.
* gnu/installer/keymap.scm: New file.
* gnu/installer/locale.scm: New file.
* gnu/installer/newt.scm: New file.
* gnu/installer/newt/ethernet.scm: New file.
* gnu/installer/newt/hostname.scm: New file.
* gnu/installer/newt/keymap.scm: New file.
* gnu/installer/newt/locale.scm: New file.
* gnu/installer/newt/menu.scm: New file.
* gnu/installer/newt/network.scm: New file.
* gnu/installer/newt/page.scm: New file.
* gnu/installer/newt/timezone.scm: New file.
* gnu/installer/newt/user.scm: New file.
* gnu/installer/newt/utils.scm: New file.
* gnu/installer/newt/welcome.scm: New file.
* gnu/installer/newt/wifi.scm: New file.
* gnu/installer/steps.scm: New file.
* gnu/installer/timezone.scm: New file.
* gnu/installer/utils.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add previous files.
* gnu/system.scm: Export %root-account.
* gnu/system/install.scm (%installation-services): Use kmscon instead of linux
VT for all tty.
(installation-os)[users]: Add the graphical installer as shell of the root
account.
[packages]: Add font related packages.
* po/guix/POTFILES.in: Add installer files.
</span></span></td><td>Mathieu Othacehe</td></tr>