okay,,, if you saying since last year you should be okay but if from last month the .....setup for a MONTH??? no the tank has not been cycled for a while now and is UNable to handle the bioload you have added to it in that short amount of time..
HERE is a list of your issues...
cycled but added fish too fast for your filtration to handle the new load....
daylights are on TOO long at most should be run 8 hours... actinics 1 to 2 hours before and after.. ONLY moonlights at night...
cut down on food.. im not sure how much your feeding but 1/2 of a commercially available cube is enough for those fish for 1 day... you could split it into 1/4 to feed morning and night each if you want..
when adding fish to a new system no matter how large or small the biological filtration has to have time to catch up with the waste your fish are creating...