head of a holding vat being aerated by com- 

 pressed air delivered through three perforated 

 plastic hoses fastened to the vat bottom. A 

 clearance of about 0.46 m (1.5 ft) was allowed 

 between pots. Fish being held for the plant 

 were present in this vat and circulated freely 

 around the pots. 



Test "B" was similar to "A" except that two 

 additional pots were used as controls to de- 

 termine if the daily disturbance of weighing 

 caused undue weight loss or mortality. These 

 two pots, one containing 90.7 kg (200.0 lb.) of 

 fish and the other 181.4 kg (400.0 lb.) were 

 weighed only at the start and at the termination 

 of Test "B". 



After the results of Tests "A" and "B" were 

 examined, additional tests were run to deter- 

 mine if different holding conditions would alter 

 experimental results. Six pots, each contain- 

 ing 136.1 kg (300.0 lb.) of catfish, were used. 

 Two were placed in a vat which was aerated 

 with agitators, two were positioned in vats 

 aerated with compressed air, and the last two 

 were put in a small, dirt, holding pond located 

 adjacent to the plant. Water temperatures 

 were 21.1° C (71° F) in both vats and ranged 

 from 8.9° to 15.0° C (48.0° to 59.0° F) in the 

 pond during testing. As in the previous ex- 

 periments, all the pots were weighed at approx- 

 imately 24-hr intervals, using the same set of 

 scales and the same procedures. 



TEST RESULTS 



All groups of test fish lost weight during 

 the 7-day holding period (Table 1). In all 

 tests the bulk of this weight loss occurred dur- 

 ing the first 3 days. Figure 3 shows the results 



72 96 120 144 168 192 216 



HOURS 



Figure 3. — Cumulative weight loss in percent for chan- 

 nel catfish held at different concentrations and in 

 different water conditions. 



of tests comparing concentrations of 320.3 and 

 640.6 kg of fish per cubic meter (20.0 and 40.0 

 lb. of fish per cu ft) of water, for fish held 

 in vats having difl'erent aeration systems, and 

 for fish held in cooler pond water. In all cases, 

 the most rapid rate of weight loss occurred 

 during the first 48 hr. Surprisingly, the 

 weights were static for almost all of the test 

 groups between the third and fourth weighings 

 (48 to 72 hr) . After passing this plateau, the 



Table 1. — Weight change in percent for individual samples. 



