Nitrates - Not NON-toxic

Written by Dr Johnson

Nitrates are a natural by-product of the bacterial "reduction" or removal of Ammonia and Nitrite in the natural pond's ecosystem. Nitrates are an under-estimated fish killer.
When fish are sick, and the history contains some information to suggest the pond has been set up for a while, you can bet Nitrate levels are part of the problem. This is especially true for Goldfish and "flipover" disease.
Once dismissed as a "non" threat to Koi and Goldfish, exceptional information exists to suggest this is not true. Scientists initially evaluating Nitrates as a toxin did not test their subjects long enough. Nitrate problems have created MAJOR reproductive problems for alligators, and other reptiles and fish, and are also immunosuppressive, invariably increasing vulnerability to diseases in the fish in the high Nitrate environment.

Nitrate accumulations cause dilation of the veins in the fins and other health problems. Nitrite is also a DIRECT guide to background pollution levels, when nitrate levels are high, there is a direct correlation to the abundance of other forms of background pollution. Think about that. If Nitrates are immunocompromising, is that right? MAYBE it's the absolute surety of other organic and gaseous background pollutions. Either way, fish in HIGH nitrate levels will be immunocompromised, have almost NO reproductive competence and will also suffere decreased growth and overall thriftiness.

Nitrates may actually be the most important measurment you make the established pond because it sets the cadence of the water changes you should do.
Never let your nitrate levels exceed 100 ppm or illness and vulnerability to disease will be the result!