Help my newts got a furry tail

[steve]

looked in on the little guys yesterday and one of them has got a big ball of what looks like fluf just before the end of his tail.

what could this be and how can i cure it?

 

[marco]

It could be a mycosis. Which is the temp ?
If little guys has metamorphosed, put them in a clean tank, containing only wet paper towel on the bottom. If they are instead in the water, put into a product used for fish against mycosis (HALF DOSE).
Let us know.

 

[steve]

the temp was 18c. i put in a new tank and put in some medication, but it died the other day. the others seem perfectly normal.