I have a bit of a problem with my Guppies. I lost a female guppy early this week and didn't think much of it as this girl was always thin and rather "shy", I figured she was always weak and eventually just gave out. But now I have noticed that Mama Blu, an older female who was pregnant about 3 weeks ago, is getting very thin and starting to look just genearlly poor. Previously she was fine and happy. The other guppies and fish look well and without any signs of problems. Does this sound like a parasite? If so how do I treat?
Tank levels -- tested weekly by the fish store and were all within normal limits as of Wednesday.
Also in the tank - Cory's, Black Skirt Tetra and Baby Blue Ram