Book of Abstracts
11th IFOAM
Scientific Conference
11-15 August 1996
Copenhagen, Denmark

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Extra Papers

Fish Farming and its Ecological Background E5

Vacha, F.

Research Institute of Fish Culture and Hydrobiology, 389 25 Vodåany, Czech Republic

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On the historical background of the Czech freshwater fishery and with reference to the used fish production technology, the study presents basic principals and limits which are necessary to implement into fish culture to obtain high quality fish. It is common carp (Cyprinus carpio) which is prevailing fish species cultured both in monoculture and in polyculture. In a polycultural system carp is cultured together with other nonpredatory-tench (Tinca tinca), bighead carp (Hypophthalmichtys molitrix), grass carp (Ctenopharyngodon idella), predatory-pike (Esox lucius) and pikeperch (Stizostedion lucioperca) fish species.

In this region water temperature ranges between 18-20$C during vegetation season. This is quite optimal for sufficient intake of natural food for above mentioned fish species. From the point of nutrition, cyprinid fish feeding mostly on zoobenthos and zooplankton contain a broad spectrum and amount of polyunsaturated fatty acids (namely eicosapentaenoic acid-EPA and docosahexaenoic acid-DHA) and less amount of unfavourable part of cholesterol. The lipid composition of the food eaten by the fish probably has the most important influence on the lipid composition of the fish. In the way of ecological system of fish culture only limited amount of commercial food, namely cereals is used.

The system and the way of fish farming limit the amount of fish from water area. The output of fish in this type of farming does not usually exceed 400 kg per one hectare of water area. The ponds involved in the ecological system of fish farming must be supplied with water of proper quality which is not eutrophic. Also maintaining of adjacent land area near pond must be in accordance with the ecosystem's stability.

The basic recommendations and principles given in the paper can help to gain freshwater fish meat of high quality. Coming into existence, a number of fish farms for which the ecological farming