Lonely Angel

One of my angel fish died mysteriously,and only had 2 now for the past months the other one looks very sad and lonely.He is about 12 cm big.I wanna know if I get a new one of similar size will it adapt and swim with the other one or will they fight.They 2 of them use to be together the whole time and thought about getting him a friend.Will it make a difference what size angel i get or not.

 

@stephen: I would not add another fish, problem is the already established fish thinks the entire tank belongs to him so adding another fish might cause them to fight and the new fish might be the looser in all of this. Don't worry fish don't get lonely as long as he has other fish to keep him company.