how big a tank is it? mine was really upset in the 10 gal hospital tank.
he was a beast in a 55. attacked everything. put him in a 20 long and now he's a chicken. loves to hang out in his ceramic pipe/cave. if i'm sitting down across the room, he'll come out and push the algea eater or crayfish away from his cave. but if i'm standing up, just to walk to the kitchen, he's back in the cave.
at feeding time he eats the blood worms that land near the cave until i walk away, then he cleans up the rest of them.
a female might give him a reason to be agressive to the other fish, but i dont know if it will make him happy to see humans.