All you basically did was check for leaks and let you water settle.. "Cycling" the tank involves introducing ammonia(fish, fish poo, food breaking down, etc).. And then the process of the water getting rid of the ammonia starts taking place.. This is usually complet in 4 to 6 weeks. Almost impossible in 5 days with nothing but water.. So what is happening right now is the fish are dying from ammonia poisoning.. THe water is not able to break down the ammonia with the bacteria iit dosen't have. You can jumpstart this process by adding some Marinelabs bioSpira. But the way you are describing the fish, they probably won't last in the tank the way it is.. Start doind 25% water changes daily(de-chlorinating of course) and look for some Bio Spira at your local fish store.. Biospira is the beneficial bacteria you need to get the ammonia ate up.. Get it? I'd also spend a few days and nights researching and reading.. I'm sure this forum will help you tremendously if you are new. As I'm sure you are finding out, ther is alot more to fish keeping than having a tank and adding fish.. Good Luck!