have they been recently added? or is their an issue with your water levels?
Ammonia, Nitrite, nitrate, and Ph may be required for us to determine what happened and what could be causing this.
please check your water for ammonia, nitrite and nitrate - the ammonia and nitrite being the most serious. Checking your water is always the first thing when you see something amiss.
It'd also be helpful to know how many, how old, and in how big a tank. Ellioti are lovely fish, but get quite territorial as they get older, so aggression could be a cause.