hurt fish

One of my glo fish attacked my yellow glo fish and took a bite out of my poor baby. I’m going to add a picture. I’ve been treating it with aquarium salt and melafix. It was very red but it’s not really now but I can’t tell if it’s healing? What do you think?

I recently adopted some rummynose tetras but they seem to be missing their back most fin and parts of their other fins as if they were in a tank with something that didn't like them. What is the fastest way to help them regrow their fin?