Rats wont stop killing eachother. Any ideas?

Are the rats in a room that has a lot of noise or activity? Sometimes that will start them killing and eating each other.

Once a rat has done that, I don't trust it. They tend to do it again. Best to do as the others have suggested and feed them off and start over with new stock.

Yeah as a rodent breeder i have seen this before if Dog food was being used mainly cheap dog food. Also are they able to reach the food? We keep 8 Weaned rats per tub (females and then we move them to $ per tub when there reach the small rat size then leave them from there but if its not the food you will need to Cull that entire group...

I agree with the others. I had a group of cannibals one time. They killed each other one at a time until I had one left. I happily fed her to my retic at the time :)