Depends in what you mean by "strange". I rarely find things to be surprising any more.
As for this particular case, it makes sense to me: the is something unique, in contrast to other categories. The lion is a mighty beast. The goldfish is not. Obviously this is a particular usage with a specific interpretation. But the extension from single-example-the is not hard to imagine. (A type-token substitution.)
Note that in general English is fairly restrictive. In many languages like Turkish and Quechua, plural expression is optional, used only when contrastive. "I read book" means "at least one" and might be used where in English we would use a plural.