CHAPTER X 



THE FOOD VALUE OF FISH 



WITH few exceptions, the different species of fishes that 

 are caught industrially are important because of their 

 food value. 



Some fishes are unsuitable for food because they have 

 an unattractive taste ; others are directly poisonous. 

 Thus, in the Japanese fish of the genus tetrodon, the 

 roe is poisonous, although the remainder of the fish is 

 edible. Some fishes are poisonous during the spawning 

 season. Others are provided with a special poison 

 gland connected with special spines or barbs. In edible 

 fishes, given the suitable conditions, poisons may be 

 formed by bacterial activity in the flesh of the fish. 

 Poisons so formed give rise to the kind of fish poisoning 

 known as botulism. Cases of botulism have resulted 

 from eating canned salmon and sardines that have 

 become spoiled. In some cases, bacteria present in a 

 diseased fish may produce poisonous substances in the 

 body of the fish. Bacillus paratyphosus has been isolated 

 from some poisonous fish, and certain poison-producing 

 bacteria have been found in others. 1 



Certain shellfish are notoriously liable to be poisonous. 

 The exact nature of the microbes concerned in the 

 production of poisonous substances in shellfish is at 

 present unknown ; it is clear, however, that such 

 poisonous substances may be produced in shellfish in three 

 ways 



(1) Microbes of various infectious diseases, such as 

 typhoid fever, may be absorbed by the shellfish from 

 sewage. 



1 Marshall, Microbiology. 



115 



