I've had a Hawaiian Dragon Eel for the past 5 years. I’m sure that the behavior between the two will be about the same so:
I'm afraid that this thing will eat anything that is half way small enough to fit into a 45g tank. It is a very aggressive Eel and I still have to be careful when feeding it as not to loose a finger. It will strike from nowhere, and if you’re not careful you’re not going to see it coming. They will make the rock work their home and rarely come out for a swim, and when they do it’s at night. I have noticed that their eyesight is very poor, and rely on smell to find the food. And there is something about stress in other fish that they can sense. I feed mine Squid, Silver Sides, Shrimp, and anything else meaty that I find. Very easy to get them to take frozen food, but the food should have a good smell to it.
They grow very fast, mine was under 12” when I first got it, and within a 1 1/2 it was over 30”. IMO a 45g tank is going to be way to small for the eel. I will probably do all right in that size tank, but it will get out sooner or later know mater what you do. Mine is in a 180g (42x30x36) tank that I had made just for the eel, nice and deep that way it would have a hard time getting out.