Hi, well the paraistes on the fish cant live without light, so it helps alot. I never used to do this ither until i found out it did charms along witht he meds and saltCan i ask how blacking out the tank cures whitespot? i only asked because i never did that. I just used the meds. Hope he pulls through. White spot is horrible to deal with. Ramjet was on deaths door and not moving and pretty much died from it but i brought him back to life with a lot of tlc and persevearance.