PROPAGATION AND DISTEIBUTION OF FOOD FlISiiES, 1923. 103 



"QUESTION MARK" AERATOR. 



Within the last yesir the dipper that 

 was used for aerating water has been 

 largely replaced by the '' question mark " 

 aerator — so named on account of the 

 bend in its handle — which is made of 

 one-fourth inch pipe and serves as an 

 air vent and means for suspending the 

 aerator in a fish can when not in use. 

 The cylinder of the aerator is made of 

 galvanized rain spouting and is 4J 

 inches in diameter by 6 inches in length. 

 The bottom contains 21 circular open- 

 ings, which are screened to prevent fish 

 from entering the cylinder. The handle 

 may be unscrewed and the device car- 

 ried in a small hand bag. 



The device provides quick and efficient 

 aeration, does not injure the fish, can be 

 used to remove sediment or to lower 

 the water in a container, and has a num- 

 ber of other advantages over the ordi- 

 nary dipper. This aerator has met witli 

 general approval, as it seems to answer 

 the bureau's needs better than any de- 

 vice that has been used heretofore. 



JET AERATOR. 



During the spring and summer of 

 1923 a new aerating device that circu- 

 lates the water in the container and op- 

 erates by air was used on the distribu- 

 tion cars to a limited extent and with 

 very satisfactory results. This aerator 

 was devised for the purpose of aerating 

 the water and removing the carbon di- 

 oxide gas given off by the fish. 



The device consists of a tube placed 

 on the inside of a larger tube, care being 

 taken to allow room enough to permit 

 the water to be forced up in the space 

 between the two tubes. Experiments 

 with this device are still being carried 

 on, and while its practicalulity is not 

 generally perceived at the present time 

 it is believed that it will be more fully 

 appreciated when further improve- 

 ments have been made in other trans- 

 portation equipment. 



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Fig. 2. — Device for circulating and 

 aeratinsr water ir tisli cans by 

 means of compressed air. 



