Well, I went to google to find out how dams ruin fish population. I found information that I was totally not expect to find.
Q: How many people have been displaced by dams?
A: Between 40 and 80 million, the majority of them in China and India.
Q: Aren’t people displaced by dams fairly compensated?
A: In nearly every case which has been studied the majority of people evicted - usually poor farmers and indigenous people - are further impoverished economically and suffer cultural decline, high rates of sickness and death, and great psychological stress. In some cases people receive no or negligible compensation for their losses. Where compensation is given, cash payments are very rarely enough to compensate for the loss of land, homes, jobs and businesses and replacement land for farmers is usually of poorer quality and smaller than original holdings.
Q: What happens when people refuse to move to make way for dams?
A: In many cases people have been forced out of their homes at gunpoint, in others they have simply been flooded out when the dam authorities started to fill the reservoir. In Guatemala in 1982, 369 Mayan Indians, mainly women and children, were murdered after their community refused to accept the inadequate compensation offered for the loss of their homes to the Chixoy Dam.