Swelling On Fin?

Fish has a lump on the base of its right pectoral fin. It's very slowly but surly getting bigger.
I noticed it about 6 weeks ago.

No way to get a pic of it as these fish don't sit still.

It's like a lump of white fat or a little like a mouth ulcer.


Fish is a tanganyikan cichlid c.leptosoma adult male pretty much fully grown at 4" approx.
these fish are very peaceful in cichlid terms, they do some times have ago at each other when competing for females.

All other fish arnt threatened by them as these are open water dwellers and they are cave and shell dwellers.

Ammonia 0
Nitrite 0
Nitrate 40-50 ( it is water change day today)
Gh 260
Kh 180
Ph 7.6-8.0

is the lump bumpy like cauliflower? it maybe lymphocyctis, this is/was rare but more and more cases of it are appearing.
 
http/edis.ifas.ufl.edu/fa181
 
http/www.fish-disease.net/diseases/lymphocystis.php
 
There is no treatment for it, I lost a whole tank of fish to it a couple of years ago. Personally remove the affected fish to another tank and hope it runs its course. So long as the mouth or gills do not get infected the fish has a chance of surviving.

What you think
?
Looks white in water and more pinky red out

It does look quite a lot like it I am afraid. If you can put him in a separate tank so it doesnt affect the others, lots of clean water (although difficult with these fish I know).