welcome to the forum, i suggest you check pacman section of the forum, there're tons of information just about everything you need to know and way more and you're welcome to ask as many questions as you like.

the only way to make him more aggressive eater if to ensure that his conditions are proper, he feels safe and food items are appropriate size. but even under those conditions majority, especially a bit older then babies, would just sit there and wait for food to come unless they're REALLY hungry