My home is in Chebei. As far as I know, there is a big market on Dongpu Avenue near Chebei (opposite to the Red Cross Hospital in Tianhe District), where there are many seafood shops. In addition, there is a vegetable market in Guangnitrogen New Village opposite to Exit D of chebei station subway (crossing the traffic lights and walking more than 5 meters), which also sells all kinds of seafood. As for the market that only sells seafood, I have never heard of it. Hope these can help you.