WATER QUALITY AND SOIL CONDITION OF FISH PONDS IN SOME STATES OF INDIA IN RELATION TO FISH PRODUCTION

Maintenance of a healthy aquatic environment and production of sufficient fish food organisms in ponds are two factors of primary importance for successful pond cultural operations. To keep the aquatic habitat favourable for existence, physical and chemical factors like temperature, turbidity, colour, odour, pH, dissolved gases like oxygen, carbon dioxide and also reducing gases Hke hydrogen sulphide, methane working lethal on fish life, will excercise their influence individually or synergetically, while the nutrient status of water and soil play the most important role in governing the production of plankton organisms or primary production in fish ponds. Rating of fish ponds on the basis of these factors is a difficult problem because of the complexities influencing and governing these factors and also for the fact that it is not possible to study the effect of any individual factor under uniform optimal conditions. Nevertheless from a study of a large number of ponds under diverse physical and chemical conditions it is possible to arrive at some broad generalisation which can be gainfully used by fish farmers. It may be remembered also that different fishes behave differently as to the suitabihty of environmental condition and food habit. As the major carps, catla {Catla catla), rohu (Labeo rohita) and mrigal (Cirrhina mrigala) are the widely cultivated fast-growing fishes in India these have been always used as standards except when otherwise mentioned.