What This Lump?

[kayisnew]

what is this lump on my tetras lip?
The fish is about 2ish yrs old, the lump has been there for about 2 months.
it is doing everything a tetra should and shows no sign of being poorly, and hasnt spread to any other fish.
any ideas?
p.s apologies for rubbish photos, little darling wont stay still!

 

[Baccus]

Not the best picture ( tetras are hell to get to stay still) but could be the start of cotton mouth.
I had a tetra ages ago that had a lump like that, nothing I tried got rid of it, and the tetra did live for quite a few months, until it eventually died.

 

[kayisnew]

just looked up cotton mouth and i havent got any of the other symptoms present, but i'll keep my eyes peeled. thanks for the reply.