If nothing else has pricked at your conscience so far; this will. This image shows only a very small sample of the millions of dead fish who turned up overnight at Redondo Beach, California, in 2011. This isn't the first time this has happened; the phenomenon occurred in both 2003 and 2005. The cause of death? Oxygen starvation. There simply wasn't enough oxygen in the water for the fish to carry on breathing.
Fish, like mammals, breathe oxygen to stay alive; they just do it using gills instead of lungs. There's only so much oxygen in the water though, and when something drains that oxygen, the fish are doomed. In this case, it was an excess of algae. Algae occurs naturally anywhere there's water, but in Redondo Beach, the algae thrived because of stimulants provided within fertilizer and other waste being dumped into the water. The algae grew too quickly, used up all the oxygen, and the fish couldn't breathe. It was a slaughter.