Well I am in the middle fo my third batch of doing this and it is simply amazing how much the fish like them. I am simply taking really old brine shrimp eggs I have had for well over 2 years, decapsulating them, then putting them in the microwave and literally popping them. They expand to a huge size, comparatively, and the fish go nuts for them. I really think that they would be an awesome first food for any and all live bearer fry as well as many egglayers if they are large enough to eat them.
Here is what I do:
I take about 1 tsp of eggs and rehydrate them in luke warm water, about 3 tablespoons, and wait for about an hour mixing them up as often as I remember to. You can do this with an airline to really keep them suspended and possibly get better hydration. Next, I add 2 tablespoons of Clorox unscented bleech or any unscented bleech and let them sit for about 10 minutes or until all the eggs have turned an orangish color. I use a large test tube I have an shake it for about 10 minutes or until I see nothing but orange eggs. The hard part is rinsing them and getting out all the bleech. I simply rinse them many, many times until I can not smell it anymore. Then I rinse them 2 more times. Before popping them, I will add some dechlorinator to make sure it is all neutralized, just 1/4 tsp. or so just to make sure. Then I put them in a coffee cup filled about 3/4 full and microwave them for 2-5 minutes or until they all turn bright red. The volume increases a lot, maybe 2-300% or more and are simply fed to the fish. The shell is no longer a worry because the decapsulating process disolved it away so you feed them directly.
I am actually gonna get some decapsulted, non-hatching eggs so that I no longer need to decapsulate them but figured I would try it to make sure it works before buying them.
If you try this, please post about and what fish you fed them to as well as how they reacted to them. I think fry will love them and be much healthier from feeding them the popcorn shrimp because the nutrition should be higher and you don't have to worry about not having enough hatched brine shrimp on hand or trying to scramble to et them hatched when an unexpected batch is found in the tank. Not to mention the problems with seperating egg cases when hatching them.