I got home today and my firefish wasn't looking too hot. He was swimming awkwardly and hanging out at the bottom. I noticed a red spot on him. I don't have a quarantine tank but if he can be saved I can take him to the LFS or leave him in my tank if it isn't a parasite or something bad.
Whatever it was he died pretty quickly. I took him out and put him in a container and was going to take him to the LFS. He was too far gone I guess. It could have happened last night because I left very early and wasn't home until tonight.
Sorry you lost the fish, but it looks like a bacterial infection, ether Columnaris or "fish tuberculosis". I would suggest to do several water changes and keep an eye on the other two fish!
Yes at least a couple 20% to 25% water changes in the next few days. Keep in mind that bacterial infections usually come from lack of maintenance or over feeding. So check to make sure all filter material is cleaned or replaced regularly, only feed what the fish can eat in about a minute twice a day and keep up on regular water changes! Good luck with your fish!