Benggai cardinals fight! Now what?

[borrowedthemoon]

My benggai are probably both males and fighting each other (fluval 13.5). I moved one into a quarantine 5 gal (not ideal) and need advice.

Do I add a female, then reintroduce the third? Or add a female to each tank?

Thanks coral friends!

 

[gbroadbridge]

A nano is not wise choice for those fish as they need at least a 40 gal tank. They grow quite fast.

I'd return them.