a farmer spray pesticides on his feild after some time he sa that fishes in near by pond die give reason of following
Answers
because pesticides are harmful for human body .
Explanation:
Fish die as a result of a wide variety of natural and unnatural causes. Fish may die of old age, starvation, body injury, stress, suffocation, water pollution, diseases, parasites, predation, toxic algae, severe weather, and other reasons.
A few dead fish floating on the surface of a pond or lake is not necessarily cause for alarm. Expect some fish to die of old age, injury, winter starvation, or even post-spawning stress in the springtime. However, when large numbers of fish of all sizes are found dead and dying over a long period of time, it is necessary to investigate and determine the cause.
Sudden, large fish kills in ponds are often the result of fish suffocation caused by nighttime oxygen depletion in the summer. Fish kills from oxygen depletion usually occur in the early morning hours (at dawn) in very rich (green water) ponds following: (1) the die-off of a large algae bloom, (2) the decay of water weeds after treatment with a herbicide, (3) the turnover of oxygen-poor bottom waters following a thunderstorm, (4) the runoff of livestock waste and other organics after a heavy rain.
Symptoms of oxygen depletion may include an abnormal distribution of fish gulping at the water surface or at the pond inlet or edges. Large fish may die first, but all sizes of fish are usually affected. The color and clarity of pond water may change and a foul odor may be released. Fish kills from pesticides, chlorine, gasoline, fuel oil, ammonia fertilizer, acids, and other toxic chemicals are not as common in private ponds, but can occur.