add bf docs
diff --git a/docs/hazmat/primitives/symmetric-encryption.rst b/docs/hazmat/primitives/symmetric-encryption.rst
index 1e047b7..94d58ee 100644
--- a/docs/hazmat/primitives/symmetric-encryption.rst
+++ b/docs/hazmat/primitives/symmetric-encryption.rst
@@ -107,6 +107,15 @@
``56`` bits long), they can simply be concatenated to
produce the full key. This must be kept secret.
+.. class:: Blowfish(key)
+
+ Blowfish is a block cipher developed by Bruce Schneier. It is known to be
+ susceptible to attacks when using weak keys. The author has recommended
+ that users of Blowfish move to newer algorithms like AES.
+
+ :param bytes key: The secret key, 32-448 bits in length (in increments of
+ 8). This must be kept secret.
+
Modes
~~~~~