Well we took the dead molly to the pet store. We decided to go to a nice independently owned one instead of petsmart. The guy there looked at the body and told us nothing on the outside was wrong, no bloating or bacteria, she looked pretty healthy. He told us to add salt and that it should be enough. We weren't positive, so we bought the stuff you recommended anyway.
Can we use parasite and bacteria medication at the same time, or will that have unwanted effects? We are only adding 1/3 the normal amount of salt because of our african dwarf frogs. On sunday we'll have an additional tank that we can put them in.
Also, I can't quite tell, but it seems like there might be flukes on one of the fish. It's blending in really strongly, so I can't tell, but it almost looks like there's little worm shaped bumps on the back of his body, near the start of the tail fin. Another fish, however, seems to be scratching, because it seems like some of her scales were rubbed off on one side.