There is a dragon goby, but it is very low salinity, a harbor fish, brackish water: it eats brine shrimp, and is about a foot long.
If you mean diamond goby, they are sand sifters and diggers.
If you mean dragonette, mistakenly called such names as mandarin goby or scooter blenny, there are two notable types, the mandarin dragonette, and the scooter dragonette. Both eat isopods. My mandarin eats 60.00 a month worth of isopods, though my tank is beginning to keep up with her demand on its own. The scooter 'blenny' dragonette is a little more willing to eat other food than pods. A mandarin's exclusivity in that department is the reason why many fail and die. Well fed, they are ich resistent, disease resistent, and generally are a personable, peaceful fish. The only trouble they tend to get into is invading some cranky fish's territory, completely oblivious to the other fish's threat displays or even fin-nips.
Do not keep a dragonette with a 6-line wrasse: the wrasse will kill them immediately.