wrote:

I have two green chromis (green chromii?) in my 55 gal. tank. I'm
considering adding a couple more. Should I expect aggression, or will
the current chromii accept their new tankmates with open fins, or?

I had 4 in my 125 gallon. They ran as a school for about a year, but one
eventually died.

A few weeks ago, I bought 3 more, bringing the total up to 6. Four of them are
hanging out together, but the two largest have become solitary. One is behaving
sickly, but I just ran a water change, and that may improve matters.

If you have lots of hidey holes, I think you'll be fine.

George Patterson
Worry doesn't improve the future; it just ruins the present.