56 Adaptations of Fishes 
In certain groups (wrasse-fishes, parrot-fishes, etc.) in the 
tropics, individual fishes are sometimes rendered poisonous by 
feeding on poisonous mussels, holothurians, or possibly polyps, 
species which at certain times, and especially in their spawning 
season, develops alkaloids which themselves may cause cigua- 
tera. In this case it is usually the very old or large fishes which 
are liable to be infected. In some markets numerous species 
are excluded as suspicious for this reason. Such a list is in 
use in the fish-market of Havana, where the sale of certain 
species, elsewhere healthful, or at the most suspected, was rigidly 
Fie. 40 —The Trigger-fish, Balistes carolinensis Gmelin. New York. 
prohibited under the Spanish régime. A list of these suspicious 
fishes has been given by Prof. Poey. 
In many of the eels the serum of the blood is poisonous, but 
its venom is destroyed by the gastric juice, so that the flesh 
may be eaten with impunity, unless decay has set in. To eat 
too much of the tropical morays is to invite gastric troubles, 
but no true ciguatera. The true ciguatera is produced by a 
specific poisonous alkaloid. This is most developed in the 
globefishes or puffers (Tetraodon, Spheroides, Tropidichthys, etc.). 
It is present in the filefishes (Monacanthus, Alutera, etc.), prob- 
ably in some toadfishes (Batrachotdes, etc.), and similar com- 
pounds are found in the flesh of sharks and especially in sharks’ 
livers. 
