Does anyone know what this white stuff is?

[eiichi]

I just got home today and noticed that one of my clownfish was towards the ground then I saw the giant white ish streak on it and am unsure of what it is or what to do. I have had them for around 3 months now and this is the first time I have ever seen this happen. Can someone please tell me what should I do or if I am overreacting because I am kind of freaking out right now.

 

[vetteguy53081]

I just got home today and noticed that one of my clownfish was towards the ground then I saw the giant white ish streak on it and am unsure of what it is or what to do. I have had them for around 3 months now and this is the first time I have ever seen this happen. Can someone please tell me what should I do or if I am overreacting because I am kind of freaking out right now.

Please refrain from cross posting which takes from others who too are seeking answers to their concern and causes confusion
Other thread has been answered