Don’t leave live fish or any food alone in a tank with multiple garters. They will fight and compete and try (and maybe succeed!) to eat each other. Get rid of the fish now! It’s a disaster waiting to happen. And whenever you feed them you MUST watch them like a hawk until all of the food is gone.

I feed my two garters separately because they are very competitive and aggressive at feeding time and the bigger one has tried to steal food right out of the other one’s mouth, which resulted in her trying to eat its head.