47 unique serial number have now been spotted.
Bit criticism of Huitong this paragraph is a bit confusing, two batches of 24 and 3rd/4th batch?
Two batches of 24 J-15s were produced. Recent images (September 2020) indicated that the 3rd batch is in service, probably for the aircraft carrier Shandong. The latest image (August 2021) suggested that the 04 batch just entered the service (starting from 74?).
49 by my own count based on various posts on this forum and including the below from Huitong via our very own @Deino