6-foot diameter and six 4-foot 

 diameter, similar to that 

 shown in fig. 11). Two addi- 

 tional wooden tanks of 4-foot 

 diameter, 2 1/2 feet deep, 

 provide storage for separate 

 lots, and two wooden tanks 6 

 feet in diameter and 3 1/2 

 feet deep are available to be 

 set up as needed for extra 

 juvenile or adult fish. The 

 fish-holding tanks are all 

 provided with running water 

 from the city domestic system. 

 Three 500-gallon charcoal 

 filters with a discharge rate 

 of 150 gpra dechlorinate the 

 water. 



A small bay of Lake Union 

 into which the holding tanks 

 discharge was dammed, and 

 here, in a 30- by 40- foot pond 

 6 feet deep, special types of 

 fish such as adult carp (for 

 blood studies) or adult squaw- 

 fish (for electrical studies) 

 are stored until needed. 



Figure 12. --Two of 9 tanks in the aqucirium room. Coils 

 in the tanks connect to the temperature- 

 control unit. Standard aquarium heaters 

 and thermostats are used to complete tem- 

 perature regulation. 



Figure 11. — A 4-foot diameter steel tank in the 

 fish-holding area. 



Conditioning and acclima - 

 tion aquariums 



Because the reactions of 

 fish to certain stimuli may 

 depend upon the environment to 

 which they have been condi- 

 tioned, an aquarium room has 

 been provided to enable us to 

 hold fish under specific tem- 

 perature and light conditions. 

 A space in a corner of the 

 laboratory wing was partitioned 

 off and equipped with nine 60- 

 gallon aquariums. Each aquar- 

 ium can be provided separately 

 with air diffusion stones, air- 

 driven charcoal filter, elec- 

 trical immersion heater, lights, 

 or a cooling coil supplied with 

 coolant from the heat-exchange 

 unit mentioned previously (fig. 

 12). Temperature can be con- 

 trolled in each aquarium within 

 the range of 0° to 33° C. 



RESEARCH IN PROGRESS 



A major part of our cur- 

 rent research is a study of the 



