I have a 75 gallon tank with an electric yellow, 2 red zebra, 4 peacocks, 4 OB and a Venustus. I bought most of them as juveniles but now discovered 1 red zebra and 1 peacock are female. The tank was getting a little aggressive since the fish are now about 4 inches and getting to breeding age. I removed the females and did an 80% water change and redecorated the tank. Before the electric yellow and a big OB were the tank bosses chasing everyone around. Since I did the water change and removed the females I noticed everyone is chasing everyone. I'm assuming they are developing the pecking order again. I also bought but haven't received 3 more male OBs for the tank,, I'm hoping this will help..