Differences between mysis shrimp brands

[Richer]

Is there a difference between mysis shrimp brands? or is a mysis shrimp a mysis shrimp?
I bought a pack of Hikari mysis shrimp for my clowns... but my clowns refuse to eat them. They would take one in, then promptly spit it out, only eating the occasional bit here and there... but leaving most of the shrimp floating around the tank. They do however, go crazy over cyclop-eeze. Are my clowns just plain picky?

-Richer