I feel for the LFS if they are a decent place. While working in/trying to buy a LFS, we got a trade in of 3 large red belly piranhas. The smallest was about 7.5in across and all three were emaciated with tatters of fins left. Supposedly, they came from an "indoor pond" of black water thet they threw a few dozen goldfish into every week or so. The two smaller rbps were barely able to swim and unable/unwilling to feed. The biggest was extremely skittish but started eating chunks of fish and shrimp. The smaller two I actually had to hold and
feed with a syringe twice a day for 3 days before they were free swimming. God was it painful trying to decide if I'd be happy to see them alive the next day. Also, I insisted they be sold as a package. (no one cared)
The little guy sold first, I think he got a good home. The middle-sized one then tore the big guy to bits and I had to put him down. The middle guy then went to some "regular" always looking for something HUGE that "kills fish" so I assume it died shortly after.
Yeah, still want to punch the owner of the store in the face for that (among other things) because *I* was in charge of fish and said these were MY take ins, and I would choose when they are sold but no one cared when a couple bucks were on the table.
All were sold on my rare days off

They still had bones showing when they left