The government has devised labels to let you know what you're buying/eating/feeding the spawn.
However you have to understand what it means and what it doesn't mean, assuming the farmer put the right stickers on them.
It's easy to jump to conclusions, shortcuts to what you want to believe.
For instance my Cheerios box boasts whole grain is the first ingredient on all Cheerios cereals.
51% Whole Grain, 49% recycled cardboard, that meets the requirements.
So does 32% Whole Grain, 29% Mercury, 29% Chlorine, but you don't want to eat it.
I'm not picking on Cheerios, I like 'em.
Caveat Emptor, always.