white spots on red minor tetra tails?
 

Some of my mollies had gotten cotton mouth so I added medication to the water and they are getting much better. I still have another dose to add, but I expect them all to make it right now. There are 5 red minor tetras in the tank also though that have white spots on their tail and fins. I can't tell a difference in the spots at all though since I added the medication. They are acting fine and they still eat like usual...no rubbing, they are still active, everything like normal. Any ideas what is causing the spots? Is is just the columnaris that has infected their fins?

It is likely Ich. Many fish can become suseptible under stress. You can treat a number of ways. The parasite is only able to be killed when it is in it's free swimming stage, and isn't on a host (fish). I would buy a good ich treatment like Quick cure (read the directions, you use a bit less for tetras). You should also raise your temps, it speeds up the life cycle. Most fish can tolerate temps to 86 degrees, but raise it slowly.

Good luck.

Gwen