By the way; incidentally — a connective used to add supplementary or tangential information to what was just said.
明日は会議があります。ちなみに開始は午前9時です。
There is a meeting tomorrow. By the way, it starts at 9 a.m.
彼はフランス語が話せる。ちなみに留学経験はない。
He can speak French. Incidentally, he hasn't studied abroad.
この映画は面白いです。ちなみに原作は同名の小説です。
This movie is interesting. Incidentally, it's based on a novel of the same name.