Not sure I understand what happened but I guess you got these two cats from a Petco for $25? That's a steal and very surprising - someone must have left them on their door step as no big chains take any trade-ins, nor do they deal with fish that big. Congratulations!
Hmm, I think I am getting it: they had three fish, two of which were TSNs. They still have one TSN... same size?? If yes, someone needs to save that poor big fish asap, I am afraid it will die very soon at Petco, if they have not euthanized it already.