Mystery Neon Tetra Deaths?

Fishery

Large Fish
Oct 5, 2004
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Sydney, Australia
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#1
Hi All.

Finally went out and bought a Fresh water Test Kit (Ammonia, Nitrites, Nitrates, PHlow, PHhigh)

Done the test with results: Ammonia 0, Nitrites 0, Nitrates 0, PH 7.5)

i'm surprised about the 0 reading for the Nitrates, test kit says that 40 and below is acceptable, but is 0 ok?

Could this be a reason why the Neons are dying? No visable signs of disease. Could it be stress due to large tetras around? I haven't seen any attacks on the neon by anything.. but occasionally the White Shirt Tetras chase the Black Widow Tetras.

what could be wrong?