“Why in the world would you have to be careful with anchovy products? It’s a fish! Not shellfish/ crustacean!” is an all too common sentiment. BUT, as is the case with many things in this world, it’s a little more complicated than that.Shrimp is a common bycatch with anchovy. I first realized this when I bought dried anchovies. And this was more common the smaller they are. The package always says 100% anchovy but if you look closely you can see small shrimp mixed in among them. It becomes more obvious when you start cooking it as the shrimp would turn red. This I’ve experienced myself.
I have also heard people saying for larger anchovy, if you try gutting them yourself, you sometimes find undigested shrimp in their bellies! if this is true it’s an even bigger problem. Anchovies are pretty much out of the picture unless they are big enough to be gutted or you gut them yourself.
Still from personal experience, I seem to be okay with fish sauce (fermented anchovy), and dried anchovy (roughly inch long and larger without unintended shrimp mixed in).
Most are fine. But there was one case where kelp bought at the source had lots of tiny crustaceans attached to it. Other than that I haven’t had any problems with commercial seaweed products.
The minefield of eating out and other randomness
Fermented shrimp paste or broths made with dried shrimp hides in many Asian foods.
An entirely unexpected case where sweet potato starch noodles (supposedly an upgraded version) had chitosan (from crab) in it. All other clear noodles I’ve tried have been fine as they were 100% sweet potato starch.