10 gal tank setup, water is good to go; tested at credible store locally as a 2nd opinion. I have a Guarami, 2 plattys, 2 guppys, and had 2 catfish until now. One of the female plattys is a butt head and aggressive. In the last 24 hrs both of my cats have died suddenly and randomly with what looks to be internal bleeding. Is someone able to explain what this internal bleeding is?