My fish are just hiding. Are they sick?

[ddp_58]

Hi so I’m new to the hobby. I am doing a fish in cycle with 4 Glofish tetras and 1 skirt tetra. I am nearing the end of the cycle and almost am done. It’s been well over a month since I have had the fish. Although they just hide and never come out. One of them comes out to eat but very rarely. The other three eat normally and come out to eat. Once there done eating they go back to hiding. I constantly have the lights off because when I turn them on they never come out. Once I turn the lights off they come out right away and swim for a bit. But then go right back into the corner. I’m guessing a sudden light change just startled them, but after the light is off they go right back into the corner. This behavior is very frustrating especially for a new fish keeper. It would be great if anyone could give me some feedback. Also I have a 20 gallon tank. I have a heater and a hang on back filter. I do not have an air pump. And I am doing my fish in cycle with Seachem prime + water changes.