Whew! I'm so glad to hear that he's fine. I've also been feeding my furkids grain free for several years now. They also try to get me to feed them more food but I have to stay strong and not give in. If I let Ziggy, Alani, Blaze, and Sky eat all they wanted, they'd be very overweight cats. Well maybe Blaze would be okay but I've already noticed that Alani is getting a bit chubby because he steals some of Blaze's food from him. Maybe you just need to feed Marlin and the others smaller more frequent meals. I currently feed mine 4 small meals a day and it seems to work for them. Good luck.