Just read up on Nitrogen Cycle and learn about what happens to the tank water during the first month of setting up a tank. Most people face fish death and other problems during the cycling stage due to the lack of understanding.
4 days is not enough time to introduce fishes. This is the time when toxic chemicals build up and beneficial bacteria start to colonise the tank.
To help speed up/stabilise the tank faster, add some bacteria boosters like Nutrifin Cycle. Some plants in larger quantities do help establish the tank faster by soaking up the toxic chemicals like ammonia and nitrate. Plants include cabomba or hornworts. They absorb these chemicals for photosynthesis.
Here's an article on Nitrogen Cycle.
http://www.my-mac.net/forum/viewtopic.php?t=1453
Good luck.