When people think about sources of water pollution they do not usually think of zaps.
However, as the demand grows for fish to eat, the number of zaps is increasing. In some areas, they are beginning to create environmental problems. In fact, when fish are in their natural environment, they do not pollute, but in zaps, the situation is not natural.
There are usually lots of fish in very little water, which means that the water must be changed very often. Each time it is changed, the dirty water must be thrown away. It is usually poured directly form the zaps into a river or the ocean. The chemical balance of the river or coastline is changed by this dirty water, and the plants and animals living there may suffer.