I give mine small cut up bits of shrimp - already cooked - usually when I am cooking it for us, I will cut up one for them. (Split 5 ways)
Mine also like chicken and fish...
My zon is funny when we have salmon. She doesn't even bother to chew, just puts her head straight back and swallows it whole! GIMME MORE OF THAT!
I stay away from giving them red meat, though one of my zons would definitely eat it if you offered it to her. (We don't)
Krill I don't know anything about.