Unresolved Help mandarin goby

i bought a very small mandarin goby today like 1 inch long maybe a little bit longer he was doing fine swimming and stuff and then my lights went off then he went to the bottom of my tank after about 3o minutes he turned like a pail white in the dark and sat for a long time now i noticed hes swimming to the top of my 29g bio cube is this bad? help please

 

I allso baught a bottle of live copepods for him to eat

 

Is this a tank bred mandarin, or wild caught? What other fish do you have in your tank, and what do you have for flow?

 

i have the stock power head that's it no other fish are in the tank and I'm not sure if it was tank bread i cant talk my dad into buying a power head he doesn't listen to me even tho i now much more about flow then he does

 

Swimming at the top makes me think oxygen problem, but I'm not sure. Does it look like it's gasping for air?

 

he has went back to his hiding spot and is laying on his rock and looks to be calm and breathing fine but hes likd white now

 

Sometimes fish turn colors at night for camouflage or when scared/stressed. Hopefully he will be ok tomorrow!

 

i found out its acshually called a Mandarin dragonet

 

Sometimes fish lose some of their color at night when the lights are out. I had Blue Green Chromis that did that.

 

allright i think he will be ok thanks for the help guys ;D now i hope i can get a good copepod colony built