Can a person fast until midday on Chanuka?
Answer:
It is forbidden to fast on Chanukah, and this includes a fast until midday — just like other days on which it is forbidden to fast (such as Shabbos and Yom Tov; see Birur Halachah 670).
The Darchei Moshe (670:2) notes that some write that for a yahrzeit one should fast on Chanukah until chatzos, but adds that this is not customary.
However, it is permitted to refrain from eating if this is comfortable or desirable for the person, as we find concerning Shabbos (see Shulchan Aruch Harav 288:3).
Best wishes.
