he needs to add more variety to its diet. one food source, unless its balanced pellets, is no good for any fish.
i dont know much about aros but i do know that feeding only one kind of worm will not be helping and could possibly be the cause.
get him to buy some carnivore sticks and crickets. try the carnivore stickes but it sounds too ill to starve onto the sticks so if it does not take them after a couple of hours move onto plan B.
use the crickets if the pellets dont get eaten. put the crickets in a tub with some chopped veg and fruit and give the veg/fruit a dusting in vitamins and mineral powders. this will gut load the crickets so the fish is getting the minerals and nutrients it needs. leave the fruit/veg and crickets in the tub for a couple of hours to get eating into the fruit/veg before giving to the aro.
once the aro is better your friend really needs to get his aro onto prepared pellets so it gets everything its body needs.