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='2018-11-11 16:19:59 +0100'>2018-11-11</span></td><td><a href='/guix/commit/gnu/packages/llvm.scm?id=89c7894805329023754512c9b30e67ceb1753cb0'>gnu: faust-2: Update to 2.5.23.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2018-09-14 15:12:03 +0200'>2018-09-14</span></td><td><a href='/guix/commit/gnu/packages/llvm.scm?id=7a20877a184b5a9794741cf49740b88d61e8a2a4'>gnu: python-llvmlite: Remove obsolete patch.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2018-08-29 17:06:13 +0200'>2018-08-29</span></td><td><a href='/guix/commit/gnu/packages/llvm.scm?id=8892cac329d3d99391ca38d9498507409cb68b36'>gnu: Add python-llvmlite.</a><span class='msg-avail'>...</span></td><td>Ricardo Wurmus</td></tr>
<tr><td><span title='2018-07-28 21:23:11 +0200'>2018-07-28</span></td><td><a href='/guix/commit/gnu/packages/llvm.scm?id=148df6052c983598a26620b660b90de93fd6039a'>Revert "Revert "gnu: llvm: Update to 6.0.1.""</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2018-04-06 17:46:03 +0200'>2018-04-06</span></td><td><a href='/guix/commit/gnu/packages/llvm.scm?id=9bdbabe963e48bcac11c053a38d990873ca48dca'>gnu: llvm, clang: Update to 6.0.0.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2018-01-18 00:09:11 +0100'>2018-01-18</span></td><td><a href='/guix/commit/gnu/packages/llvm.scm?id=6b26f9152c0c2088b2e891dadea81f5f6dc8b363'>gnu: clang-runtime: Fix build issues against glibc 2.26.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-12-25 02:01:01 +0100'>2017-12-25</span></td><td><a href='/guix/commit/gnu/packages/llvm.scm?id=ac97dce1d24e3c986c580a76148deafdf52fccdb'>gnu: check, llvm: Use HTTPS for llvm.org home pages.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>