I just got back home after being out of town for almost two weeks. My brother had been looking after my bettas using the instructions I left him, which covered all of the basics.
While I was feeding Raphael last night after getting home, I noticed that he has a strange dark area on one side of his body, about halfway down his side. In addition to being abnormally dark, that area is also raised and appears very lump-like. It's about the size of a dry pellet.
The discoloration and the bump are only on one side of his body, and otherwise, he appears to be perfectly fine. He doesn't look bloated. He's eating and swimming normally.
My brother assures me that he did not overfeed the fish, and that he stuck to my guide lines the entire time I was gone.
Raphael's five gallon tank is kept at a stable 78F, fully cycled with live plants and currently shared only with one ghost shrimp. He gets 3 pellets at each meal, morning and night. Does anyone know what this lump might be? I had planned to divide this tank to house my new veiltail as well, but I don't want to risk the new guy if this is some kind of disease.