Molly with Red spots at gills

Question
Hi!  I'm concerned about my molly.  She's developed, within the last few hours, matching large red spots on her gills (both sides).  Other than that, I can find nothing wrong with her.  I've looked up everything I can and can't find anything that fits.  The rest of the fish seem fine too (though one went missing about a week ago, I suspect it was sushi for my cats or my ferrets).  I'm concerned becuase I don't want to make it worse for the sick fish or for the others.  The fish with the problems is an older fish, but I have a baby in the tank too, so I want to get ahold of whatever it is before it spreads to the others.  I'm also concerned that if it's tuberculosis, how I do keep my other fish from catching it?  Thanks so much for your help.

Answer
Hi Kiley,

red gills are usually a sure fire signal that the tanks ammonia levels are beginning to build up. This could be due to overfeeding and/or overcrowding.

To lower the ammonia it could be worth replacing your filter media, doing a water change or buying a treatment to bring it down.

What are your current water readings??

Cheers

Tom