In the herp world there's a term known as 'gut loading'. Ie. feed your crickets fruit, veges, oatmeal for a few days prior to feeding them to anything that would eat them. That way they'll be nice and plump and have a very increased nutritional value over just buying them from the store and dropping them in the tank. I'd recommend the same for feeders of any type (i.e. goldfish, rosies, worms, etc).