One aspect of the present invention is a removable ink supply for forming a fluid connection with a fluid inlet of an ink-jet printer into which the ink supply can be installed. The ink-jet printer has a fluid conduit for supplying liquid ink to an ink-jet printhead. The removable ink supply includes a quantity of liquid ink and a fluid outlet. The fluid outlet includes (i) a hollow boss having a first end in fluid communication with the quantity of liquid ink, a neck formed in a second end of the boss, the neck defining a scaling surface and an opening; (ii) a sealing member positioned within the boss, the sealing member being movable between a first position in which the sealing member seals the opening and a second position in which liquid ink can flow through the boss opening; and (iii) a biasing structure for biasing the sealing member toward the first position. The ink supply is adapted for installation in the fluid inlet of the ink-jet printer. Upon installation the sealing member is engaged and displaced from the first position to the second position such that the sealing surface engages against a structure of the fluid inlet to create an ink seal.