Brown Spot On Glo Fish

[dodgegmc]

we just found this spot on our glo fish. he is swimming around just fine. still eating. no changes in behavior yet. I would like to figure out what this is and start treatment before it gets worse. any help will be appreciated. ive attached a pic to help the diagnosis.
thanks

 

[BerryAttack]

i believe that he was just nipped... but someone will have to expand on that..
also your fish is fat.. cut down on feeding

 

[dodgegmc]

ty for your response. I appreciate the feedback. and yes, I know he's fat.... we ended up having to call him shark bc of how he bullys the tank at feeding time  lol 

 

[BerryAttack]

when feeding time, he should be in a school of 6+ that'll help even out the aggression. also when he is at the proper weight the mark might heal on its own, but if it doesn't improve then treat with metaflex, for the slim coat etc.