Fangblenny fish aren't just a cute face. They use special opioid-based venom to avoid being eaten.
http://www.npr.org/sections/thetwo-...s-uses-an-opioid-like-venom-to-escape-enemies
http://www.npr.org/sections/thetwo-...s-uses-an-opioid-like-venom-to-escape-enemies