Rainbows are schooling fish. And in your large tank they will school quite
nicely. Especially if you do get as many as you'd like to.
You say your tank is heavily planted. Make sure there is room for these fish to
swim and school.
Rainbows are not really territorial. The dominant male can be a bit pushy at
times but I have never had one male kill another. In my planted 65gal I keep 10
large males of different species and they all take turns being the boss.
Yesterday it was lacustris and tonight it is my Skull Crk trifasciata.
One last thing be sure to buy only the best stock you can. This generally means
NOT dealing with pet stores. You have before you any number of people who could
supply you with fish or eggs. These fish are slow growers but, they are long
lived! I have adult Bosemani that I bought as adults 8 years ago! In your tank
they should grow to 5" or better. I keep all my adult 'bows at around 22C. Good
for plants, good for fish.
Chris Drew