I read the question two times (i am too lazy to read it for the third).. .but... From the title and some of the words, I think I might give You the answer...
Fish do not require special light, but some light should be provided, because they feel more comfy in it... So for the time that your lights need to be replaced, you can use sand lamp or desk lamp, stationed next to the tank (for the day hours), so the fish kinda know it is day and they should be more active... And the critters that come out at night should be hiding... The moonlight is also possible to use 24/7 if it is the only available option, but as mentioned, it might break the fish day/night regime...
OH... and lights also make the fish color pop... (the blue ones)...
Anyway, don`t stress it..