Well, the Scotter Dragonette is not really a blenny. It's actually in the same family as the Manderin and needs a good pod population to thrive. There are exceptions and mine is one of them. I was able to get him to eat frozen food. Mainly Ocean Nutrition Angel Food preparation or Formula One.
If you tank has a healthy pod population, them you should be fine. If not, I would suggest placing him in qt
and attempt to get him to eat frozen foods. If you are sucessful, then you will need to target feed him in the main. They are way too slow to compete with the swimmers for food and may starve. If he won't start eating in the qt
and your main has an insufficient pod population, then I would return him.
The psuedo is a carnivore and will eat the same foods mentioned above. Also look at the San Fransisco brand frozens and mysis shrimp.
How big is your set up?