ebjd's are very delicate fish and are prone to disease; whether internal or external. keeping them with a school of fish is always nice, but keep in mind if one of those other fishes have something, they can be easily passed on to the blues because of their weak immune system
I've raised dozens of blues from juvy to adulthood, and from experience of loosing and growing some, I would recommend keeping them alone and with very clean water/lower temps.
Also, in addition to the garlic in NLS that helps keep their internal system protected, I would recommend Seachem's Poly or Paraguard which is extremely useful for treating/ preventing external diseases in the future if you come across anything. When I added it to my tank, my blues seemed to be more active and less skittish afterwards too.
Otherwise, another reason they can still be skittish in the tank is because of the lack of beneficial bacteria built up yet. Seachem's Stability would really help if thats the case.
Then you can enjoy the amazing fish with a peace of mind knowing they are healthy

But up to you!
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