I found this doing some research on Brine Shrimp:
Brine shrimp have a fairly narrow window of high nutritional value. If one does not feed the shrimp within about 8 hours, the shrimp lose a significant percentage of the shrimp's original nutritional advantage. The shrimp use that nutritional value for their own development as it was intended, but because of their rapid development, musch of that value become waste into the water column.
I would think, based on the above info, frozen have no nutritional value at all. I'm sure the fish will eat them though.
Hope this helps!