Originally Posted by smoothie7
I added 4 a week ago today and one was dead this morning. I have heard that these guys need to be in odd numbers. I did notice that two of them had little marks on them maybe where they brushed up against a rock or something. I wander if a big fight went down last night? It was the littlest one of the group.
That sounds to me like the dead one was getting nipped at by the others. If they have little marks on them, it's not from running into things but rather getting nipped at by the dominant ones.
This happened to me in one of my old tanks. What I've done with newer tanks is introduce the chromis together with another more dominant fish (I chose a clown in my latest tank). The chromis will keep an eye on the other bigger fish rather than jockeying to see who's the boss of the tank between themselves.
Plus, once the chromis establish a hierarchy, things should settle down.