My fish are dying! What could be the problem?

you will lose fish when you cycle the tank that's why you should buy fish that are not very expensive and hearty like the danios. I would not be adding the chemicals to the tank while its cycling you need the bad and good bacteria in the tank to continue the cycle. Cycling your tank will take at least two to three weeks so be patient and stop adding chemicals. You are gonna lose fish until the cycle is done there is no way out of it. Keep checking the water every week and do water changes. when the cycle process starts to come to and end then start doing water changes to help the fish breathe better.