So I had a cardinal fish and my clown for about 3 weeks. They have been fine over the course of that time. I noticed this week that when I fed them the clown got very aggressive and began nipping the cardinal fish, chasing him away, and ate his share of food! I got home today to find the cardinal floating around with all his fins bit off and the clown actually eating him. I'm afraid to put any more fish in. What should I do?