Help with 70 gal stocking!!

[littlefoxx]

Hello, I wanted to ask if anyone out there has kept a purple firefish, scissortail dartfish and an engineer goby in the same tank? I know they all dont do well with others of their same kind? Or if one would be better with the engineer goby than another? I have a 70 gallon tank with:
2 baby clowns
Coral beauty
2 baby banggai cardinals
Baby half black mimic tang
Midas blenny

with plans to add:
Yellow coris wrasse
Lubbocks wrasse
Maybe clown fairy wrasse
Yellow watchmen goby
Engineer goby

I also have a 32 gallon bio cube with two frostbite clowns that I can put the dartfish or firefish in if there is a conflict in species.

 

[PatW]

Engineer gobies get pretty big. I would go with a smaller goby.

As for tangs, the Ctenochaetus tangs can go in a 4’ 75 gallon tank, A yellow tang might do OK. I have found that even the small tangs use all the space even in a much larger tank. So I am hesitant to crowd them.