Tetra cyst???

What is this white lumpy thing on my tetras head??

 

There are uncountable of cases alike. It doesn't seem to be treatable which points me towards a viral disease (like lymphocystis).

 

Is it contagious or fatal?

 

Don't know for sure. Experiences show there are always some in a shoal that have them and some don't. It doesn't seem ot be lethal though if they'll start having difficulty to eat there is a problem.

 

Ok thank you