The main wholesale market of Dalian seafood is Darkmouth Zi Seafood Market-it is mainly for wholesale without retail. The best place for ordinary people to buy more is Changxing Market in Changxing Street, south of Xinggong Street. There are also big food markets, but there are relatively few products.
You said that you live in Bangba Island, but there is a good place. There is a place called Shicao not far from Bangba Island. It is not far from Bangba Island along Binhai Road. As everyone knows in Dalian, Fisherman's Wharf is being built. It is a small port. There are spot seafood boats coming back every day, so you can buy it there.