Whats wrong w/ this Chromis?

[sun1914]

So a fellow reefer who I helped out with some free frags some time last year was extremely kind and returned the favor by stopping by with 5 chromis fish a few weeks ago.
After a few days of being bullied by the clowns and hippo tang everyone is getting along fine. however only 4 out of the 5 fish school. One who seems slightly bigger than the others tends to stay to myself and comes out for feeding and sometimes at night. I have noticed the hippo tang run up on this one chromis whenever he does pop his head out but the clowns do the same to the other 4 chromis sometimes and they still swim around.

Just wondering if anyone else have experience such behavior with these fish? Could it be that I have 1 different type of chromis? Black Axil and Blue/Green Chromis look alike. Maybe someone messed up

 

[sun1914]

??

 

[marrone]

It's very common that they're not going to school together, and more than likely they'll fight with each other and you may only end up with one of two. As for fish attacking just one of the Chromis, it's common that one fish gets pick on, while others are left alone. It could be from the fish size or just that it's in the area where the other fish is.

 

[fredro]

I have also seen schools of chromis to steadily drop fish, one at a time. A friend of mine bought 7 for his 150 and a year later he had 1. They would usually kinda school, but never really the way he was hoping they would. I think you'll likely find that there will always one that's the weakest and gets picked on and left out. Just from what I've seen, I'm sure someone will come on here and say that they've had 10 for 5 years that all school together. But this is what I've see first hand. Maybe see if you can find individual homes for them if it keeps up. Good luck!