To say "oni ne povas diri 'ananaso' sen 'anaso'" is more correct; with vi, you are saying that specifically the people you are talking to cannot "diri 'ananaso' sen 'anaso".
Think of it like one in English: "One must eat to remain alive" (oni devas manĝi por vivi). The one is implying that this is true for everyone; not just the audience you are talking to.
They are only related in that they both come from Latin: Anatis = "duck" in Latin; Ananas = genus for what English calls a "pineapple."
But no, I have no clue why English is the odd one out:
First you start with a d. Then you should continue on with an r. The letter a usually comes after that. Then I do believe it's a k? I'm pretty darn sure, but y'know, it's been a while. Then you finish it all off with an e, that one is your closer.
You have to say it all together though. You can't be caught dead sayin' D-R-A-K-E. People will know you're not actually a drake-sayin' expert. You gotta say it like it's one thing, real quick like. Drake. Don't drag it out. But don't go a mile a minute either so you can't be understood. Lots of beginners make that mistake and overcompensate. You have to get just the right speed. It'll take some practice and all, of course, but I've seen many a youngster get it when they thought they never would.
Here's the secret: you don't say the e. I know what you're thinkin'. You're thinkin': nuh-uh, this guy is just spouting hooey. But let me tell you, I swear on my grandfather's grave that's just how it is. You just up and pretend that e isn't there when you're sayin' it. I once asked my grandfather why this was, back when he was teachin' me to say 'drake' as a little boy, and he just got this faraway stare on this face and told me not to ask that. I never did manage to ask him again like I wanted to before he passed. I suppose the secret died with a generation that has already left this Earth. Maybe that's for the better. Some things are better left hidden, y'know? Like the man I was forced to bury out in the Mexico desert back in '53. But that's a story for another time. Whatever the reason, you darn best make sure not to pronounce that e. It's just the way it is, for better or for worse.
And don't you worry none if you can't get it right away. As a little boy I'd watch my grandfather say 'drake' and think to myself that I'd never be able to do what he did. But you get it eventually. This one young boy my age—his name was Franklin, named after the State of Franklin which is now just Tennessee, and Franklin would tell us about how his great great grandfather helped declare the independence of Franklin, 'till the government finally failed and North Carolina took over. But that's a story for another day. Leadin' a secession ain't just limited to his family either, y'know. My grandfather fought in the civil war. The 14th Tennessee Infantry. He was one of the few to survive, quite the miracle I'm around at all. He never did talk about it and I never did ask outta respect and all. One of his buddies during the war taught him how to say 'drake' when he was just 17. 'Course you had to be 18 to join the infantry, but he told them he was already 18, like a lot of young men did back in the day. There's a story that goes with that too, but that's for another day.
So anyway, this kid Franklin. He picked up how to say drake instantly. Just up and learned one day. Never did figure out how he learned so quickly. It discouraged the whole lot of us, y'know? I was struggling to learn, and everyone I knew as a young boy who was trying to learn was struggling too, and this kid Franklin just up and does it without any issue at all. And I think we all know a Franklin or two, don't we? Just someone who is so much better than you at somethin' that you think you'll never make somethin' outta yourself.
But you gotta remember: you might not be a Franklin and you'll never be a Franklin, but you don't gotta be. You'll learn just as well as the Franklins of the world if you're determined. You can become the best drake-sayer of all time if you just keep at it and believe you can. And Franklin himself died of pneumonia before he was even done with his schoolin'. I don't miss him or nothing. Not just because of the drake thing, he's the reason I'm blind in my left eye. But that's a story for another day.
And that's really all the advice I can give ya. The rest is up to you.
Oh wait, did you mean in Esperanto? Sorry. That would be "anasiĉo". The suffix -iĉo indicates things are male. A female duck would be anasino.