The invention relates to a fluid reservoir (2) for an aerosol generator (50), the fluid reservoir (2) comprising a fluid chamber (4) for receiving a fluid (6), an opening (8) for guiding the fluid (6) received in the fluid chamber (4) outside the fluid chamber (4), and a collar portion (10) surrounding the opening (8) and extending into the fluid chamber (4). A first portion (12) of the fluid chamber (4) extends along the length of the collar portion (10) in a height direction (H) of the fluid chamber (4). A second portion (14) of the fluid chamber (4) is arranged adjacent to the first portion (12) in the height direction (H) of the fluid chamber (4). A lateral extension of the first portion (12) in the directions perpendicular to the height direction (H) of the fluid chamber (4) is smaller than a lateral extension of the second portion (14) in the directions perpendicular to the height direction (H) of the fluid chamber (4). Further, the invention relates to a fluid reservoir (2') for an aerosol generator (50), the fluid reservoir (2') comprising a fluid chamber (4') for receiving a fluid (6'), an opening (8') for guiding the fluid (6') received in the fluid chamber (4') outside the fluid chamber (4'), a recess (9) arranged at least partly below the opening (8') in a height direction (H) of the fluid chamber (4'), and a cover member (30') which releasably or permanently seals the recess (9). Moreover, the invention relates to an aerosol generator (50) comprising the fluid reservoir (2, 2').L'invention concerne un réservoir de fluide (2) pour un générateur d'aérosol (50), le réservoir de fluide (2) comprenant une chambre de fluide (4) pour recevoir un fluide (6), une ouverture (8) pour guider le fluide (6) reçu dans la chambre de fluide (4) à l'extérieur de la chambre de fluide (4), et une partie de col (10) entourant l'ouverture (8) et s'étendant dans la chambre de fluide (4). Une première partie (12) de la chambre de fluide (4) s'étend le long de la longueur de la
