diff --git a/challenges/2021/06.exs b/challenges/2021/06.exs
new file mode 100644
index 0000000..5b48bbb
--- /dev/null
+++ b/challenges/2021/06.exs
@@ -0,0 +1,28 @@
+Code.compile_file(Path.join([__ENV__.file], ["../../../utils/utils.exs"]))
+
+defmodule Challenge do
+  @moduledoc false
+
+  def first_result(input), do: breed(input, 80)
+
+  def second_result(input), do: breed(input, 256)
+
+  defp breed(input, days) do
+    state =
+      input
+      |> Enum.at(0)
+      |> String.split(",", trim: true)
+      |> Enum.map(&String.to_integer/1)
+      |> Enum.reduce(List.duplicate(0, 9), fn val, acc ->
+        List.update_at(acc, val - 1, &(&1 + 1))
+      end)
+
+    Enum.reduce(1..(days - 1), state, fn _, [q, w, e, r, t, y, u, i, o] ->
+      [w, e, r, t, y, u, i + q, o, q]
+    end)
+    |> Enum.sum()
+  end
+end
+
+Utils.run(&Challenge.first_result/1, __ENV__.file, "Q1")
+Utils.run(&Challenge.second_result/1, __ENV__.file, "Q2")
diff --git a/challenges/2021/06.js b/challenges/2021/06.js
new file mode 100644
index 0000000..6aa02d0
--- /dev/null
+++ b/challenges/2021/06.js
@@ -0,0 +1,30 @@
+// Part 1
+const solvePuzzle1 = (input) => {
+  const fish = parseInput(input);
+  return breed(fish, 80);
+};
+
+// Part 2
+const solvePuzzle2 = (input) => {
+  const fish = parseInput(input);
+  return breed(fish, 256);
+};
+
+const breed = (fish, days) => {
+  let state = Array(9).fill(0);
+
+  fish.forEach((f) => state[f - 1]++);
+
+  for (let i = 0; i < days - 1; i++) {
+    const newState = state.slice(1).concat(state[0]);
+    newState[6] += state[0];
+    state = newState;
+  }
+
+  return state.reduce((a, b) => a + b, 0);
+};
+
+const parseInput = (input) => input.split(",").map((n) => Number(n));
+
+require(__dirname + "/../../utils/test.js").test(__filename, __dirname, solvePuzzle1);
+require(__dirname + "/../../utils/test.js").test(__filename, __dirname, solvePuzzle2);
diff --git a/challenges/2021/inputs/06.txt b/challenges/2021/inputs/06.txt
new file mode 100644
index 0000000..14c9317
--- /dev/null
+++ b/challenges/2021/inputs/06.txt
@@ -0,0 +1 @@
+4,2,4,1,5,1,2,2,4,1,1,2,2,2,4,4,1,2,1,1,4,1,2,1,2,2,2,2,5,2,2,3,1,4,4,4,1,2,3,4,4,5,4,3,5,1,2,5,1,1,5,5,1,4,4,5,1,3,1,4,5,5,5,4,1,2,3,4,2,1,2,1,2,2,1,5,5,1,1,1,1,5,2,2,2,4,2,4,2,4,2,1,2,1,2,4,2,4,1,3,5,5,2,4,4,2,2,2,2,3,3,2,1,1,1,1,4,3,2,5,4,3,5,3,1,5,5,2,4,1,1,2,1,3,5,1,5,3,1,3,1,4,5,1,1,3,2,1,1,1,5,2,1,2,4,2,3,3,2,3,5,1,5,1,2,1,5,2,4,1,2,4,4,1,5,1,1,5,2,2,5,5,3,1,2,2,1,1,4,1,5,4,5,5,2,2,1,1,2,5,4,3,2,2,5,4,2,5,4,4,2,3,1,1,1,5,5,4,5,3,2,5,3,4,5,1,4,1,1,3,4,4,1,1,5,1,4,1,2,1,4,1,1,3,1,5,2,5,1,5,2,5,2,5,4,1,1,4,4,2,3,1,5,2,5,1,5,2,1,1,1,2,1,1,1,4,4,5,4,4,1,4,2,2,2,5,3,2,4,4,5,5,1,1,1,1,3,1,2,1
\ No newline at end of file