[Aidevah]

There may be no universally agreed right way, but there are certainly wrong ways. "Octopuses" and "octopodes" are both acceptable, but "octopi" is wrong. "Octopuses" can be justified using Fowler's rule (from 1913!) "there is a tendency to abandon the Latin plurals, & that when one is really in doubt which to use the English form should be given the preference". "Octopodes" can be justified on etymological grounds. There is no basis to use "octopi" other than an erroneous application of the Latin rule to form plurals for second declension nouns.