I agree with Smellsfishy.
I would also add that Bait sold for fishing isn't necessarily attractive food for cory's. It is most likely aimed for the
genus, which is a different group of fish than cory's when it comes to what they normally eat...
And as you probably know, food that tastes nice isn't necessarily good for you - Shane calls this "The McDonalds effect" - tastes great, not recommended as a staple diet by nutritionists...
A varied diet based on mainly small water-insects/larvae, worms, along with pellets aimed for bottom-dwellers. Tetra Bits/Prima is a favourite amongst my fish (not just the Cory's, all my fish except the Panaque's go for it... Panaques eat wood in nature, so I don't really expect them to go wild about meaty foods - in fact I'm happy that they DON'T!).
You can make your own fish-food too. In the article linked below, there's several ideas for "carnivore" food - although that's intended for Pleco's, it's fine to use for corys too - but you'll want to make it smaller pieces (really FINE pieces, to be precise). Prawns/shrimp that are mashed up, small pieces of cooked fish, etc, etc.
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Mats