You need one of those "Don't feed the man-eating poisonous jumping spitting fish" sign or something

That stinks that someone would feed a fish not theirs.. how about a little common courtesy & respect from the co-workers.. how is his activity level and how does his belly look? Do you have a testing kit & if so, what is his water chemistry now? Maybe someone has a suggestion on a good product to help build up his strength & reduce his stress level?
He's over the finrot now, right? If so, are you adding anything to his water to prevent re-occurence and help the fins heal? The name of the stuff is on the tip of my tongue - help me please someone who's not having a brain fart on what it is called & would it help Cobalt feel less stress?
Our Bettas (other than finicky Sora) love those same flakes too. We usually feed them 2-3 of those for breakfast, then for dinner they'll have a small amount (2-3 of that night's dinner) of bloodworms, then color pellets, then betta pellets, then another kind of betta pellets with vitamins, then a half-pea dinner, then bloodworms to finish the week. Then they get a day to fast. Came up with this schedule based on advice to give them variety & try to balance the nutrients in their diet.
Hope your little guy is all-good soon and may the overfeeder of Cobalt get his head caught in the copier. :P