A fountain pen with a quick-filling coupling includes a nib assembly, a housing with a main tank and a writing tank formed therein, a rotatable finial at an end of the fountain pen opposite from the nib assembly, and a coupling for placing the housing on an ink feed device. A first sealing unit, arranged between the writing tank and the main tank, can be selectively opened and closed for filling the writing tank via the main tank. A second sealing unit, arranged between the writing tank and the nib assembly, can be selectively opened and closed for supplying ink to the nib assembly. A third sealing unit, arranged between the main tank and the coupling, can be opened and closed for filling at least the main tank. The finial is operably coupled to the pen for controlling the opening state of the first and second sealing units.