Is Bleach episode 3 filler?
Canon No, episode 3 of Bleach is canon.
#3
The Older Brother's Wish, the Younger Sister's Wish
兄の願い、妹の願い
Aired 19 Oct 2004
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.