The correct octopus plural

The whole octopuses/octopi/octopoda/octopodes issue is hilariously tragic.
There is no black and white solution as three languages are involved.

Octopus is from the taxonomic Neolatin word octopūs and zoologically all -pūs words are 3rd declension Latin and generally masculine (genitive -podis and  plural nominative -podes), because they decided so. The Romans called octopuses polypus, a masculine second declension word (plural polypi), where the pus root is the same. In other words, English pedants would have told the Romans off for not getting their Greek right —ironic given that they are fluent at it as opposed to knowing less than a smattering of rules and words.

So if problem does not lies with the Romans, does it lie with the Greeks?

Maybe… Greek was continually changing and has different periods, the Greek in Greece now speak modern Greek, whereas under the Roman empire it was Koine Greek, before that a mix of dialects which waxing and waining prestige.

An archaic dialect was Doric were the word for foot was πός (pous, genitive που, pou, plural nominative ποί, poi), a second declension, whereas in others such Ionic, the early classic one of Homer, or Attic, the classic one from Athens, it was πούς (pous, genitive ποδος, podos, and plural nominative ποδες, podes). The Romans borrowed polypus from the Doric speakers, so their plural was polypi. A similar muddle happened with the Latin letters and transliterations from Greek.

So to recap in order of decreasing idiocy:

• Octopoda.
• Pro: Yes, octopus may be a masculine not neuter, but the order is called octopoda and Stephen Fry said so on QI.
• Contra: Octopoda is for consistency and Saint Stephen does make mistakes (he got his Greek wrong on The liar by writing patrochles)
• Octopi.
• Pro: Octopus was based on polypus and that zoologists have no right to decide and ruin the purity of Latin historical continuity.
• Contra: The word was coined by zoologists, the Roman's borrowed polypi right before they went out of style, anyway, and there is no such thing as continuity with Neolatin, just anachronism.
• Octopodes.
• Pro: The correct Neolatin plural.
• Contra: Rather hard to pronounce.
• Octopuses.
• Pro: it is not the end of the world.
• Contra. But it is fun.

It is curious how the word pedantry has the Latin pedes as a root…