It’s difficult to give a definitive answer to who sells cod, herring, and mackerel without more context. To give you the best information, I need more specifics.
Please tell me:
Where are you located? Are you looking for a specific store in your city, a website, or a wholesale supplier?
What kind of product are you looking for? Fresh, frozen, canned, or smoked?
Are you looking for a particular brand or type? For example, do you want wild-caught mackerel or farmed cod?
Once I have more information, I can help you find the best places to buy cod, herring, and mackerel.