Freshwater aquaculture

Unit 6 - Sewage Fed Fish Culture

6.1. Introduction
Fish production in ponds fertilized with waste water is a common practice in some parts of Asia. Sewage fed fish culture is now well established since it is perceived to be more attractive than intensive farming. The systems include fish culture technology and sanitation engineering – it can result in substantial energy saving also.

Waste fed aquaculture dates back to more than a century in Germany where ponds receive effluents from other biological treatment systems. Net fish production from waste fed aquaculture is Germany averages 500 kg/ha/7 months, with loading rates equivalent to waster water generated by 2000 persons/ ha/yr. Munich with 233 ha designed to treat waste water from 500,000 people produces a gross fish yield of 100 – 150 mt./yr. The main fish species used are common carp (Cyprinus carpio) and tench (Tinca tinca). The German system was designed to operate in temperate regions and thus yields are low due to low stocking densities than the tropical waste fed aquaculture systems.

The concept of using aquaculture as a tool for waste water treatment has been evaluated through a systematic research programme carried out over a 5 year period by the CIFA, Bhubaneshwar. In collaboration with the Public Health Engineering Department, Govt. of Orissa, the Indian Aquaculture Sewage Treatment Plant was designed comprising of duckweed and fish culture. Three species of Indian major carps and three species of exotic carps were stocked in treated water. Production levels of 3-4 metric tons/ha/yr were realized.

In spite of the development of the Aquaculture Sewage Treatment plant, West Bengal, the only state in India where sewage fed fish culture is practiced, uses raw sewage for fish culture.

Fish is grown in Bheries using raw sewage from Kolkata city in about 10,000 ha area.