Rummy nose dying

Hi, I purchased three rummy nose few hours ago, now one died and two appear to be dying.

35L fully cycled tank,
3 Cardinal 3 ember and 1 betta,
Ammo 0 No2 0 No3 0,
Temperature 30, I'm from Malaysia so it's quite hot around here.
2 live plants which I don't know what it is.
Ph 6++

Why is it dying? I did some research and found out plenty of people don't know what's the cause.. PLEASE HELP !!

Btw I purchased ember and rummy nose and put them to my tank together. Ember seems to be fine but rummy.........

 

That's very warm for a normal community tank. Far past normal.

How long did you acclimate them?

 

That's very warm for a normal community tank. Far past normal.

How long did you acclimate them?

Haha, it's very hot here.. I put them on the water for a few hours, putting 10ml of my tank water into the bag every 5 minutes.

 

That's a good acclimation.

My best guess is the very hot temperature and/or they were weak at the store and couldn't handle moving.

 

Not really sure what's going on with your fish there, but I would advise you to keep your tetras in minimum groups of 6, and by that I mean 6 of each species of tetra, also Bettas are best left as solitary fish, so moving your Betta to a tank of it's own is a good idea.