unicorn Why do they like this kind of fish?
Puffy, the "blowfish" is a nod to the cipher Blowfish.
For a long time software created in the US could only be exported if they used weak encryption. OpenBSD, being Canadian, had no such restrictions and has always included strong ciphers like Blowfish and 3DES.
BTW, the "pufferfish" mascot was first introduced only in 2.7. Before that they had a variety of other things.