Oh My God Please Help

[lilfishie]

i have kept bettas with tetras in the past so know it can be done.
just keep a close eye on the others for any signs of anything (which i am sure you are anway)

 

[WILDER]

Bad water quality can do alot of damage.
I would check if you can see any sores on the fish that are left.
With that fish being in a bad way I would add a bacterial med to be honest.

 

[Phoenixbaby]

they all seem ok, i mean im no expert but from what i can see, no marks, lumps, or anything

 

[WILDER]

Ok see how they go.
Good luck.