There is no paint bucket tool in InDesign.
There is a proxy, however, in the bottom of the toolbox, or the upper left corner of the Swatches or Color panels, for fill and stroke color. Upper left solid square is Fill, Lower right outlined square is Stroke color. Click the one you want to bring it forward and you can use the Color panel or Swatches to apply your desired color.
You're mixing InDesign with Photoshop. Photoshop has a Paint Bucket tool under the Gradient tool. As Peter says, there is no Paint Bucket tool in InDesign.