I'll do it tmrw, when I come home from school. If there is another fight, what should I do? I don't want another hurt tetra! Would rearranging the decor help?
If your betta shows aggression, there isn't really anything you can do. Some bettas just can't live with tank mates, they are too aggressive. Rearranging the decor won't help, as the problem wouldn't be territory necessarily. Most likely just incompatibility.
What if I redecorated so the decor is new to the betta, but gave the tetras time to get used to it. Would this be an added safety?
If that specific betta has already shown aggression, changing the decor won't make him less aggressive. It could for a few days while he gets his territories set up, but once he does he will have no problem nipping if he deems it necessary.
Sometimes bettas are just too aggressive to have tank mates, no matter what precautions are taken.
Okay. Another question. My heater has enough room on the bottom to let a betta or tetra to sit under it. It is in the vertical position. Can I move it horizontal. The instructions say I can, but could this prevent this 'heater sitting' and/or distribute the heat better?