so i wanted to start a tank and thought i could just add water and fish and done so i bought a 10 gallon kit and i set it up and added let it filter for a day then i added 8 serpae tetra and 3 cory so the tank is now a week old and i found out about the cycle 4 days ago and so i added quick start now 4 of the serpae have died and they dont look too healthy and the cory are doing fine i always test the water everyday i have five plants in the tank is there anything i can do to save the fish i dont want them to die i feel bad