IMO you are fine on adding a tang. I added my blue tang first before any other fish. only problem I ever had was with a watenabi angelfish. I dont really see the tang going after any chromis or anthias. i dont know how big your QT is but yes i dont think that would be an issueSo this is my planned stock list for my 90g reef:
Current Livestock
2 x Blue Star Leopard Wrasse (Macropharyngodon bipartitus)
1 x Helfrichi Firefish (Nemateleotris helfrichi)
1 x Midas Blenny (Ecsenius midas)
1 x Copperband Butterfly (Chelmon rostratus)
1 x Matted Filefish (Acreichthys tomentosus)
Planned Livestock
1 x Fathead Sunburst Anthias (Serranocirrhitus latus)
1 x Green Chromis (Chromis viridis)
1 x Christmas Wrasse (Halichoeres claudia)
1 x Flame Angelfish (Centropyge loricula)
1 x Whitetail Bristletooth Tang (Ctenochaetus flavicauda)
My problem is that I thought midas blenny were herbivores and mine eats zero algae obviously. I feed extra heavy and I currently have no herbivores in the tank and have had a hard time keeping up with algae. I know the tang and maybe even the angel will help with that but I planned on adding them last due to aggression. I know a one spot foxface could work but that's a big bioload to add to 11 fish in a 90g (40 sump). Any suggestions for another herbivore I could add before the other fish or would adding the angel and tang before the chromis/anthias/Christmas wrasse not be a big deal?
Could I qt the flame and tang together?
Thanks!