Question

Explain why untreated sewage may kill fishes when it is added directly to a body of water.

Answer 1

because it contains some toxic chemicals and some waste waste such as plastic bag and some other type of these items which make water polluted

Answer 2

Answer:

If untreated sewage gets into river, micro organisms decompose it. They use oxygen from the water for aerobic respiration. As result is there is less oxygen dissolved in the water, so aquatic organisms such as fishes and insects may be unable to survive.