fish pox on cardinal tetra

[1873teddy]

Hi all,

My wife noticed a white growth on the tail fin & front fin on a couple of my cardinal tetra, doesn't look.like white spot but I believe it may be pox, what is the beat treatment for.this disease or have I wrongly diagnosed?

Is there a common disease among this breed of fish, all other breeds in my tank look okay.

Thanks in advance for any help/advice.