diff --git a/2021/day06/day06.hs b/2021/day06/day06.hs
new file mode 100644
index 0000000..75e548c
--- /dev/null
+++ b/2021/day06/day06.hs
@@ -0,0 +1,14 @@
+import Data.List.Split
+
+main :: IO ()
+main = do
+  input <- map read <$> splitOn "," <$> readFile "day06/input"
+  print $ day06 input 80
+  print $ day06 input 256
+
+day06 :: [Int] -> Int -> Int
+day06 input days = sum $ map (\x->last $ take x fibFish) i
+    where i = map ((+3) . (+ days) . abs . subtract 6) input
+
+fibFish :: [Int]
+fibFish = zipWith (+) ((take 7 $ repeat 1) ++ fibFish) ((take 9 $ repeat 0) ++ fibFish)
diff --git a/2021/day06/input b/2021/day06/input
new file mode 100644
index 0000000..8bed7ab
--- /dev/null
+++ b/2021/day06/input
@@ -0,0 +1 @@
+1,3,4,1,5,2,1,1,1,1,5,1,5,1,1,1,1,3,1,1,1,1,1,1,1,2,1,5,1,1,1,1,1,4,4,1,1,4,1,1,2,3,1,5,1,4,1,2,4,1,1,1,1,1,1,1,1,2,5,3,3,5,1,1,1,1,4,1,1,3,1,1,1,2,3,4,1,1,5,1,1,1,1,1,2,1,3,1,3,1,2,5,1,1,1,1,5,1,5,5,1,1,1,1,3,4,4,4,1,5,1,1,4,4,1,1,1,1,3,1,1,1,1,1,1,3,2,1,4,1,1,4,1,5,5,1,2,2,1,5,4,2,1,1,5,1,5,1,3,1,1,1,1,1,4,1,2,1,1,5,1,1,4,1,4,5,3,5,5,1,2,1,1,1,1,1,3,5,1,2,1,2,1,3,1,1,1,1,1,4,5,4,1,3,3,1,1,1,1,1,1,1,1,1,5,1,1,1,5,1,1,4,1,5,2,4,1,1,1,2,1,1,4,4,1,2,1,1,1,1,5,3,1,1,1,1,4,1,4,1,1,1,1,1,1,3,1,1,2,1,1,1,1,1,2,1,1,1,1,1,1,1,2,1,1,1,1,1,1,4,1,1,1,1,1,1,1,1,1,1,1,1,1,1,2,1,1,2,5,1,2,1,1,1,1,1,1,1,1,1
diff --git a/2021/day06/testinput b/2021/day06/testinput
new file mode 100644
index 0000000..55129f1
--- /dev/null
+++ b/2021/day06/testinput
@@ -0,0 +1 @@
+3,4,3,1,2