212 MADRAS FISHERIES BULLETIN VOL. XIII, 



thereby deteriorated in a degree which varies largely with the 

 stage of decomposition and the character of the fatty acids, as 

 will be mentioned below. Hence even originally good oil, if subse- 

 quently treated improperly, may deteriorate and lose much of its 

 value. 



But much of the oil found in Indian commerce is not good oil 

 from the beginning, but is crude, dirty, and already partially 

 hydrolysed ; this is due to the imperfect conditions under which it 

 is obtained, viz., primitive method, simple and even crude plant, 

 and dirty surroundings ; consequently it is largely of poor colour, 

 acid, rancid, full of impurities such as dirty water, mucilaginous 

 and albuminous substances, and so on. Fish oil is especially 

 liable to these evils which, moreover, result in characteristics far 

 more unpleasant than in the case of vegetable oils, owing to the 

 sources from which it is derived, the method by which it is or used 

 to be obtained, and the malodorous character of its fatty acids at 

 all events when rancidity has set in. Hence fish oil is apt to have 

 a bad name in the market as a repulsive product, and it has been 

 the object of the Fisheries Department to improve it so that it shall 

 take better rank, subserve more and better uses, and obtain better 

 prices than ordinary crude fish oil ; it is also the object of this 

 bulletin to assist in this improvement. 



I08. Fish oil, then, is derived from marine animal sources ; 

 excluding sperm oil, it is obtained mostly from the general tissues 

 such as sardine and herring oil, in which case it is called "body 

 oil " or fish oil proper as distinguished from " liver oil " which is 

 derived from the livers of various fish, such as the cod, shark,* 

 etc. In this bulletin only body oil, viz., that the oil sardine (nalla 

 matti, Cliipea longiceps) is dealt with. 



• It is curious that whereas in the cold waters of temperate climates fish oil is so 

 largely obtained from the livers of fish, e.g., of the ccd which contains no oil in its 

 tissues, in the tropical waters Vr^ashing the Indian coasts the oil is mostly in the tissues ; 

 not merely in the case of the oil sardine, but of the seer (Cybiu/n commfrsonii), varian, 

 etc. This is a serious matter in curing fish by sun-drying ; whereas cod, haddock, hake, 

 etc., when salted and dried present a white, clean, and even silvery appearance, Indian 

 dry salt fish is brown or yellowish brown of uneven colour, owing to the discolouration 

 (oxidation) of the oil which exudes from the cut tissues— when the fish is split and 

 opened out— and lies on the surface exposed to the sun and air. Such fish is preferred 

 by Indian consumers, doubtless from their experience that such fish are fat and conse- 

 quently /ro tanto nourishing, whereas colourless fish are evidently not fat ; on the other 

 hand European consumers would not look at Indian discoloured fish. 



