All very good points. Please take me seriously when I say I am very careful about water quality. All my tanks get changed weekly, and most of my tanks are overfiltered and understocked. It is not that some little fish dont make it--i have a few living gouramis, goldfish, barbs, and cories I bought a year to 18 months ago, but if I have a tetra make it longer than 3 months, or definitely 6, it is a minor miracle. On the other hand, I have a multitude of larger fish, oscars, pacu, dat, pbass, pike cichlid, natives, etc, and it is a rare day that I ever lose any of them.