Astha clocked 01:03.90 minutes in the women’s butterfly event breaking Delhi’s Richa Mishra record of 01:04.41.
The final event will be held at 5 pm today.
Earlier, sprinter Amlan Borgohain bagged gold medal in 100m race, cyclist Chayanika Gogoi won silver medal in 10km category, Nayanmoni Saikia bagged bronze in lawn bowls and Popi Hazarika won silver in 59 kg weightlifting.
The 36th National Games is being held in the state of Gujarat for the very first time between September 29 and October 12.
Nearly 15,000 sportspersons, coaches, and officials from across the country are participating in 36 sports disciplines.
Prime Minister Narendra Modi inaugurated the National Games at Narendra Modi Stadium.