What do Persian cats eat?

This is probably going to sound really daft but we took in a rescued Persian who eats absolutely everything in sight (like, he will attack my two collies until they surrender their dinners and we have to drag him away). We give him regular cat food but he eats his own and then eats the food of our other two cats also. He's not fat or anything so we just need to control him (though he can't half bite for a cat with no teeth...). Problem is... our other two cats are rescued old alley cats who like raw fish (they've caught, killed, and eaten 3 of our prize koi in the last year) and a bit of raw meat (rabbits do not sleep soundly round here...). The older two are very good and will share anything they catch with the Persian (who does not hunt at all). But then he gets horrendous diarrhoea. There's nothing like having to bath a big furry (vicious) cat... Obviously raw meat does not suit his diet but is there anything else I can give him to slow down his eating? We don't give him dry food because of the chance of him developing kidney problems. Are all Persians like this or is it purely because he was starving and close to death when we found him? He'd love to share the kill of the other animals but we just can't let him...