Many countries in Asia, also in other countries around the world, the use of sewage water and waters of inadequate quality for growing fish is an expanding business. Fishes grown in sewage water and water with degraded quality are not only a national practice but it is an export product appearing in the global market.
Poor water management, or even no management at all, is not an exception anymore but appears to be an “global practice”. This is the situation in many countries with severe sanitation, problems, limited and restricted access to clean water and major lack, even absence, of infrastructure for treatment of waste- water from industries, agriculture and household. The only alternative left in these cases for fish-farming is direct reuse of wastewater and degraded waters as wastewater is directly injected, along with dumped solid waste, to natural waters (rivers, lakes and marine coasts).
Many reports and publications in journals and public media demonstrate that food production and processing, in this case fisheries, is facing severe degradation in quality standards. Consumers in many cases are left with no information on how the fish was produced, the quality of water used in fish farming and more importantly the levels of toxic matter and compounds that exist the final product after being processed. Even in processing the fish was exposed to more toxic detergents. In southern China, for example, beneath the looming mountains of Fujian, lie dozens of enormous ponds filled with murky brown water and teeming with eels, shrimp and tilapia, much of it destined for markets in Japan and the West (http://mobile.nytimes.com/2007/12/15/world/asia/15fish.html?referer=https://www.google.se/). Fuqing is one of the centers of booming industry that over two decades has transformed it into the biggest producer and exporter of seafood in the world, and the fastest-growing supplier to the United States. As one of the farmers said “waters here are filthy and there are too many aquaculture farms, all discharging water here, fouling up other farms.”
Based on existing practices in East India (http://www.fao.org/docrep/005/Y1187E/y1187e35.htm), in this paper from Food and Agriculture Organization, United Nations, it is stated that “Sewage in India is a rich nutrient resource, cheaply available around big towns and cities. It can be well-utilized: for fertilizing paddies, fishponds and horticulture crops”. Such waste “utilization/recycling” is even considered to help maintaining a clean environment.
However, it has been suggested that professional studies should be done to assess the life-cycle of the water and the associated impacts and consequences on the environments, the agriculture and fish products. The World Health Organization WHO, in 2010 came out with a document on key issues in the safe use of wastewater and excreta in aquaculture, within its “Third edition of the Guidelines for the Safe Use of Wastewater, Excreta and Greywater in Agriculture and Aquaculture Guid”. In this document the historical and current waste-fed practice is described with consideration to all associated health and environmental issues, threats and socio-economic aspects as well as policy measures and recommendations, http://www.unwater.org/wwd10/downloads/WHO_IWA/Wastewater_WWD_2.pdf.
Though existing health, environmental and socio-economic threats of waste-fed fisheries (without wastewater treatment or using simple random treatment) there exist enormous desperation for water and fish-farming regardless water quality issues. With arguements such as “the general view that a fish grown in sewage tanks contains large number of bacteria in their body or are bacterial infected fish is ridicules as observations have proved that they are like other fish grown in fresh water ponds. Rather, the fish produced in sewage fed ponds have better taste then fresh water reared fish. The water of the sewage fed ponds, after fish harvesting can be utilized for irrigation purposes with a dual purpose of irrigation and fertilizing the field”. Unfortunately, desperation and needs force people to take huge risks not only for themselves but to expose the global market and the uninformed consumers around the world to share the same risk.
Other references exist through Google search using “fish production in sewage water” or related key words.