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You might try experimenting with lighting at the time of feeding. Many people seemed to think that theirs would initially only eat at night. Getting them to eat at this stage does seem to be the most common issue with getting them to survive.
I have a number of mysid shrimp in with them that I have put in there with them and its roughly dark in the tank (night time for me).
I do notice that of the 4 I have left- 2 look more normal in activity and seem to show more color while the other two look almost preemie-like. They are super small and almost all white.
They did not hatch in my tank but during transport. Is there any record or possibility that they could have hatched too early? I know the ones that I started with on my own were in their eggs for awhile before they hatched in my tank.
My impression from memory (without going through our posts) is that hatchings that occur during shipping fare worse than tank hatched but that is only an impression. You should be able to tell premature hatching by noticing a yellow ball held in the tentacles. This yolk sack should be fully consumed before hatching and seems to give them a couple of days of a full gut as they begin their new life.
Updated photos of two of them. I'm hoping these two make it. I am not certain but I possibly think a few mysid shrimp are missing. But hard to tell.
Curious of others opinion- I'm thinking they look like their bellies are full?