Tiger barbs died first night in clean water. Help

toust

New Fish
May 6, 2014
0
0
0
#1
Hi, Im starting out my first tank with a 26 gallon freshwater. Everything is brand new. I did some research online and decided to start with 2 tiger barbs, 2 green tiger barbs, 2 platys and an emerald
cory catfish. The water was conditioned(dechlorinated) and at 78 degress, the filter had been running for two days prior. I released all the fish into the tank about 2 pm and they were doing great for the 8 hours until i went to bed, schooling and swimming around playfully. All seemed well when i shut off the light but when i woke up this morning the four barbs are dead but the platys and catfish seem perfectly fine. I even used my ammonia tester kit even though it shouldnt be a issue the first day, there was no ammonia.

Does anyone know why this happened? Are my other fish safe?

Thanks in advance!