Algae eaters

[Chaik]

Can anyone help me I have to flying foxes in my tank and one of them started to get red "tumor " for lack of a Better word might anyone know what it is

 

[Mebbid]

It will help if you post a pic.

 

[Rivercats]

It would also help to post this in the unhealthy fish section where you will likely get more help.