the use of articles after prepositions [duplicate]

He was English by blood is correct.

It isn't true that the zero article is impossible in English. It all depends on the sentence.

No article is required here because it's a fixed expression indicating family relationship by birth rather than marriage. Example: They are related by blood. My explanation is based on CALD3.

Who taught you that there is no zero article in English?

Briefly, articles work like this:

Singular countable noun ~ ~ definite - the ~ ~ indefinite - a/an

Plural countable noun: ~ ~ ~definite - the ~ ~ indefinite - zero

Uncountable: ~ ~ ~ ~ ~ ~ ~ ~definite - the ~ ~ indefinite - zero

In detail, they work like this.