Red lump on fish tail. Does anyone know what this is??

[nmarino624]

I recently took over an aquarium that was left behind at my workplace. One of the black widow tetras (pictured here) has a weird red lump on their tail that showed up one day out of nowhere. I treated with PraziPro and then Melafix, and the melafix made it go away for a few days, but then it came back. Does anyone have any idea what it could be or how to treat it??

 

[Colin_T]

Hi and welcome to the forum

I can't tell due to my monitor being crap and everything having grey lines in it. Someone else will have to deal with this.