Octopi is equally correct because we're speaking English and frequency of use trumps etymological cromulence. Octopuses works too. I quite like "Octopods" beca

Octopi is equally correct because we're speaking English and frequency of use trumps etymological cromulence. Octopuses works too. I quite like "Octopods" because -podes is unusual in English, though not entirely absent (see Antipodes). (I'm not sure "an Octopi" is correct in any of these cases!)