Is ONE PIECE episode 605 filler?
Canon No, episode 605 of ONE PIECE is canon.
#605
Tashigi's Tears! G-5's Desperate Breakthrough Plan!
たしぎの涙 Ｇ５決死の突破作戦
Aired 21 Jul 2013
Mochibayo compiled this list from MyAnimeList's labels, because MyAnimeList's episode data is not reaching us at the moment.