Your welcome! And yes an oscar and a jack dempsey will work fine. But be warned, there will be times when the jack will hide and not eat for no reason and then the next month he will be pigging out like normal. Jacks are the most bipolar fish ever.
The colors on males are really nice! And no there is nothing you can really do. It is random. A lot of times you will see threads of people asking is there something wrong with their jack, and nothing wrong, the jack just was randomly being secluded.Is there anything i can do if that happens? I want to try get a male.