Boss Fistula
Found In
The Basement
Boss Challenge Room
Challenge Room
Normal Enemy (Later Floors)
Dropped Items
Boss Pool

Fistula is a boss that can appear in The Basement.


Fistula's only attack is to move around the room, bumping into the walls. When the original Fistula is defeated, four smaller Fistulas will be spawned, and each of those pieces splits into two even smaller Fistulas when defeated. After these smallest Fistulas are defeated, they spawn Chargers unless they are over a pit or other obstacle.

Champion VersionsEdit

  • Black: Spawns Boom Flies instead of Chargers. Pieces travel much slower, and the original Fistula will only split into three smaller Fistulas.


  • Fistula appeared in the original Binding of Isaac
  • A fistula is an abnormal connection between organs, intestines, and other tissues.
  • Fistula used to be a Caves/Catacombs boss in the original "Binding of Isaac", as of Rebirth, it is a Basement/Cellar boss.
  • The posthumous form of Fistula is Teratoma.


Bosses Boss Monstro
Basement MonstroGeminiDingleLarry Jr.The Duke of FliesGurglingsFistulaStevenFamine
Cellar Gurdy Jr.PinWidowBlighted OvumThe HauntDingleLarry Jr.The Duke of FliesGurglingsFistulaFamine
The Caves ChubGurdyGurdy Jr.Mega MawMega FattyDark OneC.H.A.D.Pestilence
Catacombs The HollowThe HuskPeepPolycephalusThe Carrion QueenThe WretchedDark OnePestilence
The Depths The CageMonstro IIThe AdversaryThe GateLokiGishWarMom
Necropolis The BloatThe Carrion QueenMask of InfamyThe WretchedThe GateLokiWarMom
The Womb Mr. FredScolexTeratomaMama GurdyThe BloatLokiiDeathConquestMom's HeartIt Lives
Utero BlastocystDaddy Long LegsTeratomaMama GurdyThe BloatLokiiTriachnidDeathConquestMom's HeartIt Lives
Sheol The FallenSatan
Dark Room The LambMega Satan
Cathedral Isaac
The Chest ???Mega Satan
Devil Room Krampus
Angel Room Angel
Levels 1-5/7 The FallenThe Headless Horseman
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