together

Hey guys! Today a put an angelfish with my betta , the angelfish looks really calm and isn't aggressive but my betta is really scared and he's trying to hide. I'm worrying about him what shoud I do to calm him down. Sometimes the angelfish tries to get close to him but he just freaks out...

I have done research on this fish and found out they're aggressive, I was wondering if two could be housed together in a large aquarium or if they would fight to the death and I just shouldn't bother. I have also been really interested in getting a Green Terror or a Jack Dempsey and I'm...