A FATALITY AMONG FISHES IN WATER CONTAIN- 

 ING AN EXCESS OF DI8S0LTED AIR. 



BY M. C. MARSH. 



For some years the fishes in the aquarium at the Woodt 

 Hole Station of the United States Fish Commission have pre- 

 sented a peculiar phenomenon consisting in the presence of gas 

 bubbles clinging about their bodies and fins. Occasionally some 

 of them developed in the membranes of the fins, or elsewhere 

 large blisters which contained a gas, and would collapse when 

 punctured. Others had bulging eyes, the affection commonly 

 called popeye. There was some mortality among these fishes, 

 but not to a serious extent, and fre.sh supplies of specimens were 

 so readily available that no serious inconvenience was caused. 

 But during the last fall and winter the losses did become seriou> 

 and the aquarium' exhibit could not be maintained without ; 

 new supply every few days, and sometimes more than half the 

 stock would die within forty-eight hours after a lot fresh from 

 the harbor had been introduced. The cleanliness of the aquarium 

 tanks was thorough and the sea water which was successfully 

 supplying the cod hatching operations, was ap]nirently the same 

 as usual. 



The species of fishes at this time common at Woods Hole were 

 the white perch, tautog, tomcod, flat-fish, and two kinds of scul- 

 pins. When these were introduced into the aquaria this curious 

 development of gas bubbles upon the fishes became evident with- 

 in about two minutes. The individual became completely cov- 

 ered with extremely minute bubbles which grew slowly larger 

 until after ten minutes they were very conspicuous and appeared 

 to envelop the fish in a delicate silvery white coating. Some 

 species were more completely covered than others but all without 

 exception developed the bubbles in greater or less abundance. As 

 the bubbles gi-ew larger they began to ho. released 1:)y the move- 

 ments of the fish in swimming, and passed off at the surface of 

 the water. Xew buljbles formed, however, to take the place of 

 those released, and the fish scldoui remained clear of them for 



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