Once, the celestial music-god Krauncha accidentally stepped on a sage called Vamadeva. The angry sage cursed Krauncha to become a mouse. However, the muni once after calming said the curse will be redeemed by a God and he will be revered too. Thus Krauncha became a giant mouse, who began to torment everyone.

Once, Lord Ganesha was invited to Sage Parashara’s hermitage for lunch. Krauncha as a giant mouse destroyed the Ashrama before Ganesha could arrive. Seeing the sad state of the ashrama, Ganesha decided to teach the arrogant mouse a lesson. Ganesha unleashed his weapon “Pasha” around Krauncha’s neck. This brought him to Ganesha’s feet. Krauncha begged for forgiveness. Ganesha forgave him and also accepted him as His vehicle. However Krauncha could not bear the weight of Ganesha and requested Ganesha to reduce his weight so that he could move while carrying his Lord. Krauncha is from then known as Mooshak or Mooshika.