will they fight

[stevieduk]

I have had a yellow tang in my tank for 3 years now, It is the biggest fish , and is the boss, although you wouldnt say aggressive. I was thinking of adding a young Koran Angel to the tank , but do you think the tang would attack it , with it being a similar shape

[GimpyFin]

Yellow tangs can be bullies, especially if they are established and you add new fish after them. Tank size can factor in as well, but IMO, there's a good chance you will have some aggression (At least temporarily.)

[nereefpat]

Yes, yellow tangs can be bullies. And yes, we need to know the tank size.