LunaReef: Yes it is a Marginallis Butterfly and they are in fact more robust. Unfortunately, I had a sickness in the tank that took him and my blonde naso tank to the netherworld. The other fish survived the outbreak (don't know what it was, but it was fast - 2 days and they were gone). Other fish in the tank showed not issues and are still very healthy.
Thank you all for the nice comments and encouragement.
Thank you all for the nice comments and encouragement.