Board Thread:Naruto Discussions/@comment-7292165-20140715160041/@comment-3422208-20140716024638

Each member of the Akatsuki is assigned a target a.k.a. their target tailed beast. The ones we know include Itachi (Nine-Tails), Kisame (Four-Tails), Deidara (One-Tails), Hidan (Two-Tails), Obito/Tobi (Three-Tails) which can be counted as Sasori's tailed beast. After losing members due to them be killed off Kisame was sent (Eight-Tails), Pain (Nine-Tails). So the assigned tailed beasts which include the (Seven Tails), (Five-Tails), the (Six-Tails) not counting the anime, and the (Eight-Tails) are the only ones we don't know. However if I were to guess, I think that Kakuzu would have probably been assigned the (Seven-Tails) being he was from Takigakure and knew how to get into the village.