[formerly_proven]

You really should never eat shellfish from unknown sources, because these are either from unsustainable farms pumped full with chemicals to keep diseases in check or from the sea. Either way, very dirty food in more than one way. If you really gotta eat shellfish, get it from local closed-cycle industrial farms. That's of course more expensive, because you're paying for what you're getting.

[GordonS]

As someone that did a lot of research into aquaculture for work a couple of years back, I'm now very picky about where I get fish, whether finfish or shellfish.

Safety, processes, practices and quality vary wildly by region and farm.

[mrosett]

Do you have any high level suggestions?

[GordonS]

I'm in Scotland, and in general I'll select wild fish from Scottish waters or farmed fish from Norway, as the Norwegians have very good standards.

I'll also swerve fish (such as salmon) from Chile, as standards are relatively low there - for example, they permit a much higher sea lice count than anywhere in Europe.

For shellfish, I prefer wild Scottish sources, but Scottish farmed is OK too. I'd swerve shellfish (typically prawns) from Bangladesh, as despite farming often being done in a small scale, standards can be low.

[MandieD]

Farmed salmon from Norway is the main kind available at fish counters in German supermarkets, so that’s good to hear.

[halpert]

I was pretty impressed with Maine's lobster catch regulations. Most notably, the license holder has to be the one to physically pull up the traps, which puts a very small upper bound on how big a single lobster catching operation can be. They also have catch regulations to keep the practice sustainable, which makes sense given that it's a large part of their economy.