I had 3 fish die on me during the night,i know i have a little bit of white spot in the tank,at first i just thought it was the male swordtail,then noticed a guppy lying on the bottom of the tank,so when i lifted out a plant to get at it there was another guppy dead in the plant,so i have treated them for white spot third day of treatment and also increased the temp in the tank...when i looked at the 3 dead fish it looked as if they had no white spot on them,if so what would of caused them all to die?