The Kapil Muni Fair is the largest fair of Bikaner district held on Kartik Poornima at Kolayat--originally Kapilayatan--named after the sage Kapil who is believed to have done tapasya (meditation) here for the redemption of mankind. Kolayat is situated in an arid area. Ther is a lake with 52 ghats shaded by banyan trees around the lake. A temple dedicated to Kapil Muni is situated on the Kapil Muni ghat and it has a marble statue of the saint.

It is considered very auspicious to take a dip on Kartik Poornima in the Kolayat lake. Visiting Kolayat has been considered to be a tirtha or pilgrimage of great importance and it is believed that one day's stay at Kolayat benefits as much as 10 years spent at any other sacred place.

A cattle fair is held in conjunction with the Kapil Muni Fair. Buffaloes, camels, horses and cattle are sold. Certificates and prizes are given away to the best breeders at the fair.