diff --git a/README.md b/README.md
index cf5bf1f..1d3ccf3 100644
--- a/README.md
+++ b/README.md
@@ -15,6 +15,7 @@ helpfiles in the `doc/` directory. The helpfiles are also available via
 * [Clojure](https://clojure.org/) ([zprint](https://github.com/kkinnear/zprint))
 * CSS, Sass, SCSS, Less (js-beautify)
 * Dart (dartfmt)
+* Fish ([fish_indent](https://fishshell.com/docs/current/commands.html#fish_indent))
 * Go (gofmt)
 * [GN](https://www.chromium.org/developers/gn-build-configuration) (gn)
 * HTML (js-beautify)
diff --git a/autoload/codefmt.vim b/autoload/codefmt.vim
index 9624e14..fd6a3b5 100644
--- a/autoload/codefmt.vim
+++ b/autoload/codefmt.vim
@@ -30,6 +30,7 @@
 "   * c, cpp, proto, javascript, typescript: clang-format
 "   * clojure: zprint
 "   * dart: dartfmt
+"   * fish: fish_indent
 "   * gn: gn
 "   * go: gofmt
 "   * python: autopep8, yapf
diff --git a/autoload/codefmt/fish_indent.vim b/autoload/codefmt/fish_indent.vim
new file mode 100644
index 0000000..795b3b4
--- /dev/null
+++ b/autoload/codefmt/fish_indent.vim
@@ -0,0 +1,48 @@
+" Copyright 2020 Google Inc. All rights reserved.
+"
+" Licensed under the Apache License, Version 2.0 (the "License");
+" you may not use this file except in compliance with the License.
+" You may obtain a copy of the License at
+"
+"     http://www.apache.org/licenses/LICENSE-2.0
+"
+" Unless required by applicable law or agreed to in writing, software
+" distributed under the License is distributed on an "AS IS" BASIS,
+" WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+" See the License for the specific language governing permissions and
+" limitations under the License.
+
+
+let s:plugin = maktaba#plugin#Get('codefmt')
+
+
+function! codefmt#fish_indent#GetFormatter() abort
+  let l:formatter = {
+      \ 'name': 'fish_indent',
+      \ 'setup_instructions': 'Install fish_indent (https://fishshell.com/docs/current/commands.html#fish_indent)' .
+          \ ' and configure the fish_indent_executable flag'}
+
+  function l:formatter.IsAvailable() abort
+    return executable(s:plugin.Flag('fish_indent_executable'))
+  endfunction
+
+  function l:formatter.AppliesToBuffer() abort
+    return &filetype is# 'fish'
+  endfunction
+
+  ""
+  " Reformat the current buffer with fish_indent or the binary named in
+  " @flag(fish_indent_executable), only targeting the range between {startline}
+  " and {endline}.
+  function l:formatter.FormatRange(startline, endline) abort
+    let l:cmd = [ s:plugin.Flag('fish_indent_executable') ]
+    call maktaba#ensure#IsNumber(a:startline)
+    call maktaba#ensure#IsNumber(a:endline)
+    " fish_indent does not support range formatting yet:
+    " https://github.com/fish-shell/fish-shell/issues/6490
+    call codefmt#formatterhelpers#AttemptFakeRangeFormatting(
+        \ a:startline, a:endline, l:cmd)
+  endfunction
+
+  return l:formatter
+endfunction
diff --git a/doc/codefmt.txt b/doc/codefmt.txt
index 4f55739..b9a219e 100644
--- a/doc/codefmt.txt
+++ b/doc/codefmt.txt
@@ -111,6 +111,10 @@ The path to the zprint executable. Typically this is one of the native images
 installed as zprint.
 Default: 'zprint' `
 
+                                              *codefmt:fish_indent_executable*
+The path to the fish_indent executable.
+Default: 'fish_indent' `
+
                                                     *codefmt:plugin[autocmds]*
 Configures whether plugin/autocmds.vim should be loaded.
 Default: 1 `
@@ -154,6 +158,7 @@ The current list of defaults by filetype is:
   * c, cpp, proto, javascript, typescript: clang-format
   * clojure: zprint
   * dart: dartfmt
+  * fish: fish_indent
   * gn: gn
   * go: gofmt
   * python: autopep8, yapf
diff --git a/instant/flags.vim b/instant/flags.vim
index 865082c..6ddb884 100644
--- a/instant/flags.vim
+++ b/instant/flags.vim
@@ -128,7 +128,6 @@ call s:plugin.Flag('rustfmt_options', [])
 " The path to the rustfmt executable.
 call s:plugin.Flag('rustfmt_executable', 'rustfmt')
 
-
 ""
 " @private
 " This is declared above zprint_options to avoid interfering with vimdoc parsing
@@ -148,3 +147,7 @@ call s:plugin.Flag('zprint_options', function('s:ZprintOptions'))
 " images (zprintl or zprintm) from https://github.com/kkinnear/zprint/releases
 " installed as zprint.
 call s:plugin.Flag('zprint_executable', 'zprint')
+
+""
+" The path to the fish_indent executable.
+call s:plugin.Flag('fish_indent_executable', 'fish_indent')
diff --git a/plugin/register.vim b/plugin/register.vim
index 66486b0..91b5c52 100644
--- a/plugin/register.vim
+++ b/plugin/register.vim
@@ -36,3 +36,4 @@ call s:registry.AddExtension(codefmt#buildifier#GetFormatter())
 call s:registry.AddExtension(codefmt#googlejava#GetFormatter())
 call s:registry.AddExtension(codefmt#shfmt#GetFormatter())
 call s:registry.AddExtension(codefmt#zprint#GetFormatter())
+call s:registry.AddExtension(codefmt#fish_indent#GetFormatter())
diff --git a/vroom/fish_indent.vroom b/vroom/fish_indent.vroom
new file mode 100644
index 0000000..9681d33
--- /dev/null
+++ b/vroom/fish_indent.vroom
@@ -0,0 +1,96 @@
+The built-in fish_indent knows how to format fish code.
+If you aren't familiar with basic codefmt usage yet, see main.vroom first.
+
+We'll set up codefmt and configure the vroom environment, then jump into some
+examples.
+
+  :source $VROOMDIR/setupvroom.vim
+
+  :let g:repeat_calls = []
+  :function FakeRepeat(...)<CR>
+  |  call add(g:repeat_calls, a:000)<CR>
+  :endfunction
+  :call maktaba#test#Override('repeat#set', 'FakeRepeat')
+
+  :call codefmt#SetWhetherToPerformIsAvailableChecksForTesting(0)
+
+You can format any buffer with fish_indent specifying the formatter explicitly.
+
+  @clear
+  % if test 42 -eq $truth; echo '42 is truth'; else; echo 'I do not know what to believe'; end
+
+  :FormatCode fish_indent
+  ! fish_indent .*2>.*
+  $ if test 42 -eq $truth
+  $     echo '42 is truth'
+  $ else
+  $     echo 'I do not know what to believe'
+  $ end
+  if test 42 -eq $truth
+      echo '42 is truth'
+  else
+      echo 'I do not know what to believe'
+  end
+  @end
+
+The fish filetype will use the fish_indent formatter by default.
+
+  @clear
+  % function f; echo f; end
+
+  :set filetype=fish
+  :FormatCode
+  ! fish_indent .*2>.*
+  $ function f
+  $     echo f
+  $ end
+  function f
+      echo f
+  end
+  @end
+  :set filetype=
+
+It can format specific line ranges of code using :FormatLines.
+
+  @clear
+  % function foo; echo "my name is:"; echo "foo"; end<CR>
+  |function bar; echo "my name is:"; echo "bar"; end
+
+  :1,2FormatLines fish_indent
+  ! fish_indent .*2>.*
+  $ function foo echo "my name is:"
+  $     echo "my name is:"
+  $     echo "foo"
+  $ end
+  $ function bar echo "my name is:"; echo "bar"; end
+  function foo echo "my name is:"
+      echo "my name is:"
+      echo "foo"
+  end
+  function bar echo "my name is:"; echo "bar"; end
+  @end
+
+Errors are reported.
+
+  @clear
+  % function f;
+  :FormatCode fish_indent
+  ! fish_indent .*2> (.*)
+  $ echo test error >\1 (command)
+  $ 1 (status)
+  ~ test error
+  function f;
+  @end
+
+The name or path of the fish_indent executable can be configured via the
+fish_indent_executable flag if the default of "fish_indent" doesn't work.
+
+  @clear
+  :Glaive codefmt fish_indent_executable='my_fish_indent'
+  % function f;
+  :FormatCode fish_indent
+  ! my_fish_indent .*
+  $ function f
+  function f
+  @end
+  :Glaive codefmt fish_indent_executable='fish_indent'