Black spot on clown fish

[OdinCorals]

Hi,

Suddenly there is a black spot on my clown fish, they are very happy and healthy, eat every day and do not seem sick.

I have not introduced any fish for months, only 2 clown fish and a mandarin are in the tank, some shrimp, snails and a crab. nitrates are 0-1ppm.

I did introduce a new coral, a rock full of zoas, could it be stings? photos attached.

thanks all!

 

[Crabs McJones]

Could by hypermelonization from being stung by a new coral.

 

[OdinCorals]

Could by hypermelonization from being stung by a new coral.

ok, I will monitor them daily to see then. I heard it might be black ich, must no new fish in the tank, there is no way ich is introduced..