Can Bearded Dragons Eat Fish?

No, they should not eat fish.

Although it wouldn't kill them to eat a small amount of it, fish is not found in their natural environment and can carry harmful bacteria, germs, and even parasites that could infect your dragon. Fish, just like other meats, is a protein-rich food source, and overfeeding them protein can cause health problems such as gout and other illnesses.

Because it isn't their natural food source, there haven't been any studies done on the effects that fish have on your dragon over time and as with anything you feed your dragon, if you aren't sure about it, then it is safer not to let your dragon eat it.