Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
When you were adding stuff to make it cycle, were you feeding the bacteria? Were you adding ammonia?
If not, then no matter how much bacteria in a bottle you added in the first week, over a 3 week period they died and there were not many left when you added the fish.
If you were doing a proper fishless cycle, then you were probably fine adding that many fish; Properly done, the fishless cycle grows a LOT of bacteria.
Exactly which parameters were 0 after 3 weeks? After a good fishless cycle the nitrate is usually sky high, requiring a water change before adding the fish.