These are convicts. They will pair up as long as you have a male and female. No need to get more fish for a tank that is too small anyway.
They are convicts. That's what they do. Aggressive little fish.
Agree. When fully grown,and 29,30 or bigger would be best.
Fry are tiny. You will need to grow them out in a 10. Having three or four 10 gallon tanks will let you let them grow to a descent size.