6 months is typically the time at which they develop their "adult" appetite. That means that starting now, you can expect to see him not eat every day of the week.
Many people feed exclusively crickets or almost exclusively crickets. An animal is not going to refuse to eat because it is bored of the food an animal is going to eat when it is hungry.
It's true that an animal that is not really hungry might be tempted into trying a new or eating a "known to be especially good" food, but that does not equal the animal not eating when it's hungry. That's more like when we manage to cram in dessert because--despite the fact that we filled up on dinner--that piece of cheesecake just looks so good.