I just saw the movie, and I can’t understand why it has this title.
First of all, A whale is not a fish! Is the word translated as “fish” used for all swimming animals? Even if that’s the case, any idea why the movie producers would use a patently incorrect translation?
And a begonia is a small herbaceous plant, that in no way resembles a big tree. I think the big flowering tree is what the title is supposed to refer to, as one of the items on the Blu-Ray (a supplemental feature or a song; I don’t recall) gave it as Big Fish and Chinese Blooming Crabapple. I’ve tentatively identified it as Malus spectabilis. So, what’s all the talk about begonias?