Found the smaller of the two clowns (the darker coloured one) dead this morning

I'm not exactly sure what happened. Neither of them have been eating since I picked them up (I did see them eat at the LFS), but I figured I wouldn't worry as it's only been a couple of days. The larger one was always shaking and dancing around the smaller one, but the little guy always seemed to ignore the big one. I'm wondering if the larger of the two decided to kill the little guy? Or maybe it was just stress... Hopefully the one I have left starts eating. A big water change is also in order tonight as the death has caused an ammonia spike
