Number one natural is meal worms and superworms from the pet shop. Superworms skip the small fish but if the big ones are there work just as well as meal worms. Mealworms get bit easier when fish are slow to bite. Eathworms don't work for me anymore and that's weird since I caught plenty on them as a kid. Bread works great too but they nip at it.

I like the white food source grubs previously discussed for a synthetic but want to try the gulp too. Used gulp at the coast without much luck compared to natural.