Only problem is that brine shrimp have little nutritional value - even with enrichment.
Sorry but that statement is factually incorrect.
The nutrient value of live brine changes from newborn through to adult.
To start with, the egg sack is the source of the fatty acid (lipids) that many want for their fish or corals, and this begins depleting imediately upon hatch.
In the first stage, the nauplii have no mouth or anus so they cannot feed, except off the egg sack, and, they cannot be gut loaded at this point.
After the first molt the nauplii can be gut loaded but it takes 24 hours for 2nd stage naupli to gut load completely.
It's best to gut load in 2 stages, with a complete water change and new nutrient for each stage.
As the nauplii go through their stages, the fatty acid (lipid) levels decrease, but the protein level increases. Also, as they progress through to adult, the time to gut load decreases to the point the adults will gut load in about 1 hour.
Now, as adults the myth is that brine shrimp have no nutrition. It most likely comes from people looking at the frozen brine shrimp package and reading the percentage protein. Any frozen brine shrimp I've seen, have percentages based on WET weight, while mysis and almost all other foods often report their nutrient levels in terms of DRY weight.
Just think, if you use a flake food, as soon as you put it in the water, it now soaks up tank water and has a higher moisture content, like the already wet brine shrimp. The flake food won't be dry when your fish eat it.
Great Salt Lake cultured brine shrimp will have protein levels close to 60% based on DRY weight.
For FACTUAL information on brine shrimp nutrient see this United Nations article
BRINE SHRIMP NUTRITION
For the most complete factual information on all aspects of brine shrimp, see the total article on Artemia in this UN article which is just a part of a paper on live foods for the aquaculture industry where brine shrimp, both nauplii and adults, are used as a part of the feeding programs for raising fish and shrimp for our food market.
CLICK HERE AND SCROLL DOWN TO SECTION 4.0