As for my Greek comment, here is an excerpt from Wikipedia on the subject:
My university course in Latin and Greek in modern English (circa 1960's) was intentionally pedantic and considered "octopi" as an objectionable hypercorrection. As for the Wikipedia justification, all editors with whom I have dealt would require "octopus" to be italicized, if it were used as the Latin scientific name. Thus, that use would be easily identified in text (but not in speech

). I meant my comment sort of tongue in cheek. I use "octopuses" most commonly, sometimes "octopodes" just to show I was awake occasionally in that long-forgotten class.
Plurals in American English are easily made by rule (e.g., "octopuses"); although, some might sound a little funny, look strange, or require context to know they are plural. One such example taken from electronics is "LED's." That spelling can be either a plural or a possessive depending on context. Sometimes, the plural is written "LEDs" for which there is little ambiguity.
In sum, what is correct is what the editor decides. It is useless to argue with an editor's decision.
Now, back to practicing everyday English. OK?
John