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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<tr><td><span title='2022-08-11 00:21:11 +0200'>2022-08-11</span></td><td><a href='/guix/commit/gnu/packages/boost.scm?id=b424ca573df717acc7d5a074b69218eaaeb19ce3'>gnu: mdds: Update to 2.0.3.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
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