I have a 20gal long (L: 20in, W: 9in, H: 12in). It is housing a 2.5 in male con and a 1.5 in female. And a 1 in zebra danio. Cons are soo aggressive that they murder any goldfish I put in there. Is there space in this tank to add any more fish so they can all fit in there at full adult size? What is compatable with my cons in a tank that size for life? Feel free to give answers based on your experiences or opinions, Im still new to fish so any help is welcome. Also they havent mated yet, the male just keeps chasing the female. When and will they ever mate? Thanks.