. Mass killing of fishes occur in

(a)           eutrophic lakes.

(b)          fast flowing river.

(c)           salt lakes.

(d)          oligotrophic lakes.

Best Answer

(a)        eutrophic lakes.

A eutrophic lake is a lake with high primary productivity, the result of high nutrient content. These lakes are subject to excessive algal blooms, resulting in poor water quality. The bottom water of such lakes are commonly deficient in oxygen, ranging from hypoxic to anoxic; thus, such lakes commonly lack those fish species, like trout, which require cold and well-oxygenated water.

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