Not much. General consensus is that unless gut loaded brine shrimp are pretty much useless.
of course I've never studied the nutritional content of shrimp so i am just responding based on what I've read.
Unless you are raising babies or seahorses I'd just stay away from brine. Sometimes if you have a difficult fish to get eating you may need to use live brine to get it started, but I'd go with mysis. Brine are like candy. empty calories.
Live brine can be useful for getting finicky eaters to eat, and it is easier to boost the nutritional value of (by gut loading it). But plain brine, versus frozen brine...eh. I suppose you can make and argument it is like fresh veggies versus frozen veggies. Many will always claim fresh is better...but it is in this case still a low nutrient food either way.
usually frozen is harvested at a point where they still have their yolk sac then froze which makes them more nutrient rich along or the are gut loaded like ophiura says. in general there are much better options available as far as food goes than brine shrimp.
I have been feeding my fish brine and ORA Pellets for the clowns. thats all they would eat, I have 3 chromis and 2 clowns, No one would eat the flakes or the mysis last time i tried, the frozen mysis was to big for them.
What should I be feeding them??? I dont want to create something, i just wanna pic up something at the store and feed them, what should it be if not brine??? My resources are limited at my LFS's lol
the frozen brine has additives.. not sure what the additives are, but if you notice in the frozen cubes, there is frozen liquid.. its obviously not brine juice.. some people make claims that the added liquid increases phosphates in their system..