No! Do not plug a vibratory aquarium air pump into a dimmer.
The little air pump is just a vibrator that presents an inductive load to the dimmer and most dimmers don't like that sort of load at all. They want to see a resistive load to be happy. It will damage either the dimmer or the pump or both, possibly in a spectacular fashion.
The magic smoke that all electrical stuff depends on to function properly will escape and stink up the joint.