Simply remove the cap to fill them.

for:

Pixma IP 7200 Series;  Pixma IP 7220;  Pixma IP 7240;  Pixma IP 7250;  Pixma IP 7270;  Pixma IP 8700 Series;  Pixma IP 8720;  Pixma IP 8740;  Pixma IP 8750; Pixma IX 6800 Series;  Pixma IX 6820;  Pixma IX 6840;  Pixma IX 6850;  Pixma MG 5400 Series;  Pixma MG 5420;  Pixma MG 5440;  Pixma MG 5450;  Pixma MG 5470;  Pixma MG 5500 Series;  Pixma MG 5520;  Pixma MG 5540;  Pixma MG 5550;  Pixma MG 5560;  Pixma MG 5600 Series;  Pixma MG 5620;  Pixma MG 5650;  Pixma MG 5655;  Pixma MG 6300 Series;  Pixma MG 6310;  Pixma MG 6320;  Pixma MG 6340;  Pixma MG 6350;  Pixma MG 6400 Series;  Pixma MG 6420;  Pixma MG 6440;  Pixma MG 6450;  Pixma MG 6460;  Pixma MG 6470;  Pixma MG 6600 Series;  Pixma MG 6620;  Pixma MG 6650;  Pixma MG 7100 Series;  Pixma MG 7120;  Pixma MG 7140;  Pixma MG 7150;  Pixma MG 7160;  Pixma MG 7170;  Pixma MG 7500 Series;  Pixma MG 7520;  Pixma MG 7550;  Pixma MX 720 Series;  Pixma MX 722;  Pixma MX 724;  Pixma MX 725;  Pixma MX 920 Series;  Pixma MX 922;  Pixma MX 924;  Pixma MX 925