Nope it's in their nature better to rehome himI have a similar issue. I had 2M + 2F BosemanI rainbows, noticed the big male was chasing the smaller male constantly. I re-homed a pair of the rainbows, keeping the aggressor (the biggest and purdiest, though maybe that was a mistake). I then added a pair of turquoise rainbows (1M/1F). Now the boisterous male BosemanI chases both the turquoise. My question is, with a boisterous male BosemanI like this, would adding a second female calm him down?
Yup, I've always kept at least 5 (60 gallon tank). The only time I had an issue is when the 2nd male came of age to breed. They fought over females for maybe a week. Everything is back to normal now.Quick update: I rehomed my turquoise pair and added two more BoesemanI males plus three females (total 3M, 4F) to my planted 55G. All is well now - Boisterous Male has mellowed out. So it looks like having a critical mass of the same rainbow species definitely can have a big impact. Others have of course known this forever; I apparently like to learn the hard way