My wrasse has a problem

[lanreef]

My wrasse seems having a swelling on the lateral side of the body, it is not a sore or even an attack of viral diseases. It is like a lump, I've just notice it today, It has some ich but I can treat it. But the problem is that swelling in its body, it is clearly seen even in the distance. Kindly tell me what is it? What cause it? Is there any remedy about this? Is this a tumor? What do you think?