Ammonia spike killed half my fish. Lessons learned.

Posting this so others can learn from my mistake. I added too many fish too quickly to a system that had not fully cycled. Ammonia hit 4ppm before I caught it and lost about 60 fish overnight. The biofilter just could not keep up. Should have been more patient. If you are starting out, do not rush the cycling process. It takes 4 to 6 weeks minimum.