There are many self-service seafood restaurants in Mianyang, the following are some of the more popular ones:

1. Self-service seafood on the third floor of Wanda Plaza: Located on the third floor of Wanda Plaza in Mianyang City, it provides a variety of seafood and self-service Haagen-Dazs ice cream, lunch price is 139 yuan/person, dinner price is 169 yuan/person.

2. Yuanli Thai Seafood Hot Pot: Located at No. 32 Huayuan Road, Fucheng District, Mianyang City, it provides Thai seafood hot pot and self-service snacks at relatively affordable prices and a clean and tidy environment.

3. Chanweixuan Seafood Buffet BBQ: Located at No. 29, East 2nd Lane, middle section of Fujiang Road, Jiangyou City, Mianyang City, it provides seafood buffet BBQ and self-service snacks with moderate prices and a beautiful environment.

4. Manningxiang Thai Seafood Hot Pot: Located at No. 91, East Section of Binhe Road South, Fucheng District, Mianyang City, it provides Thai seafood hot pot and self-service snacks in a beautiful environment and fresh ingredients.

5. Yirenyikou Steak and Seafood Buffet: Located at No. 6, Linyuan Road, Fucheng District, Mianyang City, it provides a steak and seafood buffet and self-service snacks with a beautiful environment and fresh ingredients.

To sum up, there are many choices for buffet seafood restaurants in Mianyang. You can choose different restaurants to try according to your personal tastes and preferences.