I once saw a 10 gallon tank with guppies in it where the person never changed the water. The water in that tank was so dark that all I could see was the eyes of the little ones that where born there swimming close to the glass. I tired to talk to this person about this but all I got was a shoulder shrug and a walk away. She is my niece. At a later date when I stopped by for a visit the tank was gone and I never saw it again.
The adults had long since died in that tank, but they had off spring that was born there. They survived for awhile, but then all died due to as is my guess high ammonia, and other bad pollutants in that tank. The point is the off spring survived as long as they did, because they where born in tank. But they didn't live long enough for off spring of their on.