I have a single dragonette in my tank, which is a little bigger than yours. It seems happy because it has been in there for a couple of months and looks healthy.
Ideally, you will need a healthy copepod (pods) population. You can either feed pods regularly or work to establish a reproducing population. The latter requires a mature tank and most likely regularly dosing live phytoplankton.
I’ve read that some people are successfully feeding them other foods. If want to go that route, I’d make sure that they are feeding on that food in the store before purchasing it.
Another thing. You said dragonettes, as in more than one. Be careful because they don’t get along well with other dragonettes with exception, I’m assuming, of the opposite gender.