In the wild, bearded dragons are omnivores, eating a mixture of invertebrate and vertebrate prey (such as insects and smaller animals) as well as plant material. In captivity, they should be fed a combination of insects (mostly crickets, with a variety of other cultured insect prey) and greens and vegetables.
Bearded dragons are prone to impaction of their digestive system, and the chitinous exoskeletons of insect prey can cause problems. This is especially true of crunchy bugs like mealworms, so it is best to feed these in limited quantities, especially to juveniles. Feeding insects right after a molt will help reduce the chance of an impaction as the exoskeletons are not as tough. Crickets also should not be too large, especially for baby bearded dragons (a rule of thumb: feed nothing bigger than the distance between the bearded dragons eyes). Once bearded dragons become adults, you can offer a wider range of insects such as waxworms, silkworms, butterworms, red worms, earthworms, and newly molted mealworms and superworms. However, these should be considered "treats" with crickets still making up the bulk of the diet. Pinkie mice can also be offered to adults occasionally.
Juveniles should be fed insects more often than adults. Feed jubeniles at least twice a day, offering as many appropriately-sized insects as they will eat in 10 minutes or so. Don't feed until the tank is heated up in the morning or just before the tank cools down at night, as the heat is necessary for digestion. Adults can be fed insects once a day (for both juveniles and adults, greens and vegetables can be available all the time).
Insects should be gut loaded (fed nutritious food that is then passed on to the lizard) prior to feeding, and lightly dusted with a calcium and Vitamin D (no phosphorus) supplement at each feeding. Dust with a complete multivitamin no more than once a week.
It is risky to feed wild caught insects due to the risk of pesticide contamination.One caution: do not feed fireflies (lightning bugs) or boxelder bugs as these are believed to be toxic to bearded dragons!
Greens and Vegetables
In addition to insects, bearded dragons should be fed a mixture of green leafy vegetables (e.g. dandelion greens, collard greens, chickory greens, mustard greens, turnip greens, escarole, parsley), other vegetables (e.g. squash, carrots, green beans, peas, bell peppers), and some fruits (e.g. berries, apples, grapes, cantaloupe, papaya, mango, blueberries, bananas). The plant portion of the diet should be about 20-30% of the diet. These items can be chopped up and mixed together to make a salad, which can be fed in a shallow bowl. Leafy greens can also be clipped to the side of the cage.
Commercial diets are becoming more available, but so far the long term success of these diets is not well known. It is always best to feed as varied a diet as possible, so if these prepared diets are used they should just be a supplement, not the sole source of nutrition.
As mentioned, bearded dragons are generally docile, and can be easily handled with minimal socialization or effort into taming. It is important to scoop them up under the belly and support their belly in the palm of your hand with your fingers gently curled over the body.
Their nails do get sharp, and should be trimmed regularly. They can be trimmed in a similar fashion to iguana claws.