Healthy rat bullying his less mobile cage mate

[Boomeringue]

I have two male rats aged around 2 years and 3 months. In the last few months one of them has been gradually losing the use of his hind legs. It's meant I've had to adapt the cage and how I feed him, but he's ok for the time being. The problem is the other rat, who is still fully mobile and very (hyper) active has started bullying the disabled boy. They tend to be fine when they are in their sleeping hammock together, but any time before, during or after feeding time, the active rat will push the disabled rat onto his back and pin him down aggressively. There is nothing the disabled rat can do about it, and afterwards he just stands there with his fur puffed out looking terrified and traumatised. It's heartbreaking to see.

Can anyone offer any advice? I try my best to keep them apart during feeding times, but it seems that the active rat will just wait until they are back together and then start bullying him.

 

[Boomeringue]

I've kinda managed to get on top of this by changing their feeding routine to ensure they are always separate when they're eating, and by making sure that I am always watching them around feeding time.