On Friday I added 3 Angelfish (all about 2 inches) to my tank. They seemed OK, had started to settle in and eat a little. But last night when I got home 2 of them were dead. I examined them and the living one. There were no obvious marks or damage on any of them. My tank is a 55 gallon and has been cycled for about 6-8 weeks. pH is 7.8, ammonia 0, nitrites 0, nitrates 10ppm. These were the same readings I got on Monday when I tested and Friday prior to adding the Angels. The other fish in the tank are 3 Pakistani Loaches and 5 Harlequin Rasboras, they all seem fine, active and eating. The only change I could see was that the temperature of the tank had risen from it's normal of 79 degrees to 82 degrees. I know it was 79 on Monday night, I record the temperature when I record my water chemistry readings. Could the temperature change of 3 degrees over 24 hours have killed them? Can anyone help me with things to look for? I'm quite upset because these were my first "cool" fish and I wanted them to be the centerpiece of my tank(they also cost about $10 each ). Any ideas, suggestions or comments will be very appreciated. Thank you.