Cycling!

[Captain Retardo]

No, its just that Ammonia kills fish...Ammonia will build up because fish produce it...If you did no water changes at all then the ammonia must have really built up...That's all.

 

[OohFeeshy]

There's no logical reason, it's just sheer luck. You might have got a hardy group, but the majority would nbe killed pretty soon.

 

[adam98150]

After the cycle i started doing weekly water changes.