They should be okay in your tank upgrade, I have my red devil x Midas paired up in a 75gl, they just spawned a few weeks ago, I'm in the process now of growing the fry out,Right now he's in a 55 gallon divided with a female both small so they got tons of room yet. Have a 75 gallon and 90 gallon ready to move when they out grow. He had a fader female with him they were paired up at previous owners house and they were fine I brought them home and he killed her in the first night I was sad the female was beautiful didn't show any signs of aggression when I had watched them.

