Why does 鱼 come before 做 in this sentence? I'm reading the book "301 Conversational Chinese Sentences".

At Lesson 20, this sentence appears: "这个鱼做得真好吃". 

鱼 should be the object, and 做 should be the verb, right? "Fish" cannot do the cooking itself.

Could you tell me why the verb 做 comes after 鱼?

Edit:

I found an article on this:
https://resources.allsetlearning.com/chinese/grammar/Degree_complement
Degree Complements with Objects

Exactly what I am looking for.
There is the "topic-comment structure" in Chinese:


  In a topic-comment sentence, the usual word order is rearranged a bit, in order to emphasize a certain part of a sentence. The part that is to be emphasized becomes the topic and moves to the beginning of the sentence, with the comment on the topic coming after the topic has been stated.


So here the topic is "这个鱼", which is the object of the verb. And the subject (who cooked the fish) is just omitted from the sentence.