Is ONE PIECE episode 541 filler?
Canon No, episode 541 of ONE PIECE is canon.
#541
Kizaru Appears! A Trap to Catch Tiger!
黄猿登場! タイガーを狙う罠!
Aired 1 Apr 2012
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.