After talking to Doug and a little reading this thought came by so makes some sense. Just here me out please.
Small amounts of Dioxins, a hazadous compound, are produced naturally forest fires, volcanoes. The majority of Dioxins are a result of human industrial process such as production of certain herbicides, waste inceneration, pulp processing at paper mills, agriculture sprays and many others.
Each individual, humans now, seem to have their own tolerance levels. But Dioxins are documented to build up in fish flesh as well.
Now, the most common acute effect of Dioxin exposure on Humans is, chloracne, a severe skin rash characterized by acne-like lesions.
So that would explain the hit or miss concept. Would take a certain amount of time in the life of a fish to show tolerance level or lack of. Shows in the form of acne-like lesions. Some towns or ponds may be in closer contact with such toxins.
If this is the case, indoor or roofed ponds would have less chance for cotamination perhaps. Just a thought. |