Ill Mbu Puffer

Hi all,

I have inherited a Mbu puffer and have had him for about 4 weeks now. His black colour seems to have gone alot and patchy. he has been like this for about 3 weeks but seems to be eating fine. He is about 5-6" long. Here is below in all his glory and happy but now he has faded. I did notice he was being bullied by some other fish but I have passed them on to another tank so they dont bother him anymore.

I have also had columaris/mouth fin rot in the tank about 3 weeks ago but that seems to have all cleared up over 2 weeks ago

Any Ideas?

Tank size 120 X 71 X 51 just under 400 litres

Amonnia 0
Nitrite 0
Nitrate 20-30ppm
PH 7

Stress due to bullying can make a fish ill.
I would soak his food in some garlic to boost his immune system.
Any signs of flicking and rubbing.
Is it possible to load of pic up of the sick fish.