well, you can cycle a tank and keep the ammonia levels down.
if yu have little die off, and the tank cycles-ok, thats fine. NOW, in theory, lets say ya put nothing in the tank-but its done cycling.
some of the bacteria will die because there is no ammonia, so YES that is right!!! if you 'feed' that same tank (heck, pee in it=protiens and ammoniea going into it) that same tank will have a higher bacteria colony.
since he added so many fish at one time, there will be a constant source of ammonia that the bacteria need ANYWAY, with or without water changes. yes, water changes will bring this down, but bacteria can only reproduce SO fast. Thats why it takes so long for tanks to cycle. The bacteria eat, then split, then eat, then split. Its limited in both how fast it goes because of the reproductive cycle of the bacteria, and how much ammonia is in the system over time.
If the fish were suddenly removed in, say, two days, there will still be ammonia for a week. The bacteria will peak at that time, then.. when the ammonia falls off, the bacteria will begin to die off. Thats when the nitrite becomes higher than the ammonia... hence the cycle
sorry, I was a biology major, and understand that part of relationships between food-predator...