hey guys, heres the story. 3 swordtails and two bristlenoses in my tank died last week!!! only 1 swordtail and 1 bristlnose survived.(both in hospital tank...) I cleaned out my tank, replaced the gravel with finer gravel, changed the water with 50% fresh water, 50% water from my other clean angelfish tank. I bought 4 cardinals, the next day, the cardinals lost their red colour!!! What happened?