I've had my pair living happily together now for about 3mths, both fish are approx 20mths old, anyway they have always been close...until lately, he has been a bit of a bully but nothing too major, went out today, came home and he had nearly beaten her to death , I quickly moved her out. He has given her a real hammering....but why would he do this to her now after months of placid living?? Can I put them back together at any point of time??