Is ONE PIECE episode 554 filler?
Canon No, episode 554 of ONE PIECE is canon.
#554
A Great Clash! The Straw Hat Crew vs. 100,000 Enemies
大激突！麦わら一味ＶＳ１０万の敵
Aired 1 Jul 2012
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.