Experiment: Put the printer toner in a glass of water and move the magnets around the facade of the glass.
Observation: The toner starts to move in the direction the magnet goes. It keeps attracting to the magnet until the magnet is removed away. It is a water trick where you can play around the water with a magnet whatever way you want.
Explanation: The reason why this fluid is magnetic is because the printer toner contains iron-ball ink (ink that contains dissolved iron particles). The iron particles are attracted to the magnet.