Introduction and Literature 



As coEznonly used the term "poisonous fish" has a veiy broad meaning and 

 there is no apparent agreement among the various interpretations of it. I 

 consider it proper to interpret the term as having a general application to all 

 species vAiich have poisonous substances contained in their bodies and which 

 directly harm the human body, rtiether by the contact of their bodies or by 

 the eating of their flesh or viscera either fresh or some time after their 

 death. These fishes f«ill naturally into two categories depending on the loca- 

 tion of the poisonous substances in their bodies. The first type includes 

 those species which take some positive protective action. Their poison is con- 

 tained in special spaces at the bases of the fin spines and is injected into 

 the victim by the action of muscles when the spines are touched. Poisons of 

 this type may be veiy violent, but the flesh of such fishes causes no reaction 

 irtiatever. 



The second type are fishes in irtiich the protective function is passive. 

 These are the species which are comTsonly called "poisonous fish". If the flesh 

 of these fishes is eaten, poisoning results and in many cases it is fatal. 

 The location of the poisonous element varies somewhat in different species, 

 but it is chiefly found in the gonads, particularlir in the ovaries, or some- 

 times in the liver. For this reason if sufficient care is taken in preparing 

 the fish for the table, the flesh may be eaten without any ill effects. The 

 poison in these fishes is not produced until the fish reaches maturity and is 

 most violent in its action during the spawning season, 



% orders were to Investigate the fishes in the latter category. Present- 

 day organic chemistry cannot provide any satisfactory answers regarding the 

 poisonous elements in these fishes. None of the characteristics of their com- 

 position have been made clear. Among past studies of poisonous fishes are the 

 following on the balloonfish, which has been known in Japan since ancient 

 times: in 1889 Takahashl and Inoko studied the symptoms of poisoning in animals 

 and investigated methods of isolating the poison. Later Dr. Naruml Inoue 

 studied the curative properties of the poison, end in recent years Dr, Fusao 

 Ishihara made a physiological study of balloonfish poison. Dr, Ryojun Tahara 

 succeeded in refining balloonfish poison and it is employed as a nediclne at 

 present under the name of "Tetrodotoxin." 



It is not very widely known that among the fishes of the tropics, parti- 

 cularly among salt-water fishes, there are many that are poisonous. The only 

 study of ffich fishes of which we have any knowledge is the 1925 import try 

 Ryuichl Matsuo from Jaluit I. irtilch »a8 mentioned above. For seven months be- 

 ginning in August, 19ZA, ISatsuo utilized his leisure from his medical duties 

 to make a detailed study, but he did not succeed in clarifying the problem. 



In the report of marine biological researches aboard the special duty 

 vessel KBfshu in the South Sea Islands in 1933 it was noted that "In the Caro- 

 line Islands there are no poisonous fishes except the balloonfish. Fish taken 

 by angling from the ship were eaten, after being identified by the Fisheries 

 Experiment Station of the Government-General, and no cases of poisoning re- 

 sulted, " Dr, Amemlya (1921) has repoz>ted on fishes with poisonous spines. 



Thinking that the only way I could operate would be to observe the actual 

 conditions in the field and then bring back with me the snterials for ny ex- 

 periments, I took along with me some of the instruments and chemicals which 

 would be needed in the expeidaents. C^N I 1 In the tropics it is particularly 

 essential that dissections of fishes be carried out with the utaost expedition, 



190 



