Help me

[Tspors58]

You can say that a rope connects point A to point B. But if that rope is only clothes-line, and a 250 lb man tries to use it, it may break. If you put 2 fish into a tank that has just cycled, you are putting a lot of biological 'weight' on a very thin rope. Cycling is not a date by which things work: it's a process that actually goes on for 6 months or so, in terms of becoming fully alive and strong. Start slowly with snails and micro-hermits and increase their number while you prepare a fish in quarantine.

Correct cycling is not a date however, just because the numbers made the turn does not mean it is ready. It takes time for that cycled turn to become stable. I never test for a cycle no sense to test if you wait for your system to settle. Therefore the 2 month - 4 months works and the water is much more stable to support fish,

 

[jminick2]

so much bad info on this forum for new people anymore.
IF a tank is properly cycled and can process ammonia under 24 hours a fish is absolutely 100% not going to die overnight from ammonia poisoning. I don't care if you add the day after your cycle or 2 years later, this fish did not die from ammonia poisoning, if everything is as the OP says of course.