Bir* ?
Bir fil seversiniz.
?

Because the English refers to a certain elephant that is liked by that person.

Does the English sentence not seems strange?
If it's about one sertain elephant, it should be "You like the elephant", or it's about elephants in general, it should rather be "You like elephants"...

No, it doesn't seem strange.
The English sentence is possible, for a situation in which you don't need or it's not important to mention the specific elephant that one likes.

Of course, the other two sentences that you mentioned are also possible, but they refer to different situations.

I'll give you an example:
Look, I like a human being, while you like an elephant.
How come you like an elephant?
:-)

Maybe there is an "are" missing in the English sentence?
(just kidding)

I added a context for this sentence. See above. ☺

"Bir fil seversiniz."

is less natural.

But, we can translate like this:
"Bir fil seviyorsunuz."

Which means: You love an elephant. ☺

Is it now good, Eldad?

Thanks to all.

"You look like an elephant." It was the first, I thought about. :)

Eldad, here is a special thank to you, I can't ever imagine such examples.
It can be even: "Mom, I fell in love with an elephant" :)

Celal, çok iyi. ;-)
Selena, that's a great example! :-)