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><th>author</th><td>Nicolas Goaziou &lt;mail@nicolasgoaziou.fr&gt;</td><td class='right'>2021-05-09 21:53:12 +0200</td></tr>
<tr><th>committer</th><td>Nicolas Goaziou &lt;mail@nicolasgoaziou.fr&gt;</td><td class='right'>2021-05-09 21:53:12 +0200</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/guix/commit/Makefile.am?id=0623de06fb7635d8920e9b0a18e63231bf63f8fc'>0623de06fb7635d8920e9b0a18e63231bf63f8fc</a> (<a href='/guix/patch/Makefile.am?id=0623de06fb7635d8920e9b0a18e63231bf63f8fc'>patch</a>)</td></tr>
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<tr><th>parent</th><td colspan='2' class='oid'><a href='/guix/commit/Makefile.am?id=069399ee9dbf75b7c89583f03346a63b2cfe4ac6'>069399ee9dbf75b7c89583f03346a63b2cfe4ac6</a> (<a href='/guix/diff/Makefile.am?id=0623de06fb7635d8920e9b0a18e63231bf63f8fc&amp;id2=069399ee9dbf75b7c89583f03346a63b2cfe4ac6'>diff</a>)</td></tr><tr><th>download</th><td colspan='2' class='oid'><a href='/guix/snapshot/guix-0623de06fb7635d8920e9b0a18e63231bf63f8fc.tar.gz'>guix-0623de06fb7635d8920e9b0a18e63231bf63f8fc.tar.gz</a><br/><a href='/guix/snapshot/guix-0623de06fb7635d8920e9b0a18e63231bf63f8fc.zip'>guix-0623de06fb7635d8920e9b0a18e63231bf63f8fc.zip</a><br/></td></tr></table>
<div class='commit-subject'>gnu: img2pdf: Update to 0.4.1.</div><div class='commit-msg'>* gnu/packages/pdf.scm (img2pdf): Update to 0.4.1.
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