Originally Posted by jbeatts
In that sized tank, I doubt there will be any issues. In the wild, cardinal species can often be found mixed but when you add breeding into the mix, there's where you can run into trouble, and more trouble in small tanks. That said, your Bangaiis may stop spawning because they are mixed. But if you see them paired off and away from the other Cardinals, I wouldn't be alarmed as that may be them finding a place to spawn.