I need some advice.

Hello everyone, I just set up an 8 gallon rimless tank, with sand and LR. The inhabitants are: a candy cane pistol and a yellow watchman. I also have a green one-head hammer. I used water from my older 55gal mixed reef. I was wondering: I want to add one or two more small fish. Any suggestions? I know its a small tank, but I know they're some smaller gobies. I have a high-output WavePoint light on it also, and I want to add some corals so-- I need help with that also.

I want to add some kind of powerhead for some movement but I figured I'd need a nano-sized one that I'd have to order online, so any suggestions?

Thank you so much!