3. Giant livestock farms, which can contain hundreds of thousands of pigs, chickens, or cows, produce lots of waste -- often equivalent of a small city. While a problem like this sounds pretty ridiculous, pollution from livestock farms seriously threatens humans, fish and ecosystems. Below are some facts and stats about the pollution: From 1995 to 1998, 1,000 spills or pollution incidents occurred at livestock farms in 10 states. 200 manure-related fish kills resulted in the death of 13 million fish. Manure from dairy cows is thought to have contributed to a contamination of Milwaukee's drinking water in 1993, which killed more than 100 people, made 400,000 sick and resulted in $37 million in lost wages and productivity.

5. Large fish farms have large discharges of excrements and excess fish food. Discharge of nutrients like nitrogen and phosphorus boosts this process by fertilizing the biomass production in the water. Changes in water quality may also affect the living things (fishes) in the water. The fish may not adapt to the new water quality and die. But now most of the farms today are placed on deep localities with good water replacement, and the problem of overloading sea areas has been reduced in relation to the early years of the aquaculture.