Incandescent lamps for aquariums are typically for the very small tanks.  Normally 10 gallons and under.  Most of these type of tanks can be fitted with regular fluorescent bulbs as well.  Incandescent lamps typically give off little or no UV radiation at all.  UV is required by plants, algae (beneficial or otherwise), and coral to survive properly.  If you tank is so small that it does not have a flourescent available for it you may be able to substitute a desk halogen lamp for this instead.  It is advised if you do this to ensure there is some type of plastic or glass cover over your tank, you keep the lamp at least 3-5 inches above the glass and remove the UV filter from the bottom of the halogen desk lamp.  This MAY be suitable depending on the size of your tank.  (You may need a second one or some other variation of a DIY (do it yourself) contraptions to complete this.