I have recently started a tank about three weeks ago. I started with three RNT and two dwarf rainbow peacocks which all have been doing great except one got ich which I treated for and was gone after three days. Since the start I have slowly added fish a blue coral hifin and a red platy then a dwarf gourami and later a sunset platy. All the fish were happy, just the hifin and plays were a little shy which was normal for being just introduced to the tank. But all of a sudden I am re aquatic aquascaping my tank and move a plant and one RNT floats to the top just out of the blue. I was nervous so I bought a test kit and my ammonia was at .25 nitrate and nitrite both very low and ph round 7.5 which to me I think are all acceptable ratings. The next day I see another RNT by the top of the water floating and breathing extremely fast, little to say it died the next morning but it was stuck to the intake of my filter in which I recently opened up more could that be what killed them? Because this afternoon that's where I found the third one that to me looked like nothing was wrong with him up until then. HE even eat this morning. PLEASE HELP! 
