White spot on my clownfish?

I noticed a small white spot once I got the fish home a couple weeks ago. It has since grown in to this. Can anyone identify what this is through this picture.

 

I found this for you:

Q: My fish have an off-white looking substance growing on the fins.
A: This is a gram-negative bacterial infection called Columnaris Disease. Some people often mistake this disease as a fungus.

Treatment: Sulfa drugs work well for this. TMP-Sulfa -or- Sulfa 4 TMP -or Triple Sulfa Powder.

Q: The fins on my fish are all fuzzy and cotton-like. The fins are eaten away.
A: This sounds like a Saprolegnia Fungus.

Treatment: Treat the fish with Forma-Green for 5-7 days.

I got it from this website:

Fish Fin Disorders

 

i may be wrong but from the looks of the sand and rocks i'm believing this is a new tank and this may be the first fish, clowns are very prone imo to disease and need the tank to be aged before introducing him to it, water quailty and temp is the most important things, I hope he pulls through its hard to say what he has at this point