Goldies don't have much of a stomach, Their digestive tract is like a long tube... so more frequent, smaller meals work best. Feed too much and lots of poop comes out the back end only partially digested. Some people say to feed an amount as big as their eyeball... that should be around a stomach full of food.
Here are a couple of pics from when I necropsied one of my little goldies who didn't make it. Be forewarned, they're graphic, but they'll give you a better idea what the digestive tract looks like. (
1,
2). That clearish sack is the swim bladder. The brown squiggly tube near the bottom is the GI tract.
It'd be good to broaden their diet. A good sinking pellet combined with fresh veggies, etc. Flakes make my guys have floaty poop and they actually flip my big moor.
