Over the years I've had a number of tanks w/ different groups of chromis, I've never once had an issue keeping them long term, my longest kept group were 6 that I had for 6 years and only lost them due to equipment failure.
I presently have 5 in my 120g, all healthy, bright colors, and they are probably the tightest grouping I've had so far, they are pretty much always in a very tight cluster.
It's been said they may not be handled properly in shipping due to being an inexpensive fish, and that may be a factor, also they are prone to uronema.
One thing I have always done is get them pretty small, and they are usually first in tank as they are an easy way to get your tank looking stocked w/ out a great expense.
I've had long term success w/ both odd and even groups, so I don't take stock in that theory, I don't think they can count!lol...but ya never know...
I presently have 5 in my 120g, all healthy, bright colors, and they are probably the tightest grouping I've had so far, they are pretty much always in a very tight cluster.
It's been said they may not be handled properly in shipping due to being an inexpensive fish, and that may be a factor, also they are prone to uronema.
One thing I have always done is get them pretty small, and they are usually first in tank as they are an easy way to get your tank looking stocked w/ out a great expense.
I've had long term success w/ both odd and even groups, so I don't take stock in that theory, I don't think they can count!lol...but ya never know...