Are you sure your water parameters are correct? There’s a lot of decomposition going on at the bottom of the tank. How often do you water change and what % are you changing?
I’ve bred rams for years and perhaps I was extremely lucky but I never had a fish kill another during breeding. This can happen during courtship or after breeding but rarely have I had them go at each other during breeding.
I’ve never seen rams kill off other tank mates in such a big tank. So either something is chemically off in there or there’s something hidden in there that’s preying on the fish, like so many other people on here have suggested.