siiTvived beyond 8 hours, were sampled about 8 hours after beginning 

 the experiment. The second samples for bacterial counts were taken 

 either immediately after the death of the last fish in the container 

 or after 30 to 312' hovirs providing one fish survived the test period 

 (3I2" hours). The .10 containers sampled for bacterial counts included 

 all of those which were sampled for such counts initially (3, 5, 

 6, 9, 11, and 12), the container of uhialgal G. brevis (1), the 

 container of sea water (2), and the two containers of non-aerated 

 G. brevis cultures (4 and 7). These samples were plated after 

 15 to 90 minutes refrigeration. 



Following the collection of bacterial and G. brevis samples, 

 all test materials were sampled for dissolved oxygen, pH, and 

 salinity determinations (Table 7), Aeration of each container 

 (if aerated) was discontinued just before collecting the samples, 

 which were taken either immediately after the death of the last 

 fish in the container or near the end of the experimental period 

 if at least one test fish survived. Seven containers (2, 5, 8, 

 11, 12, 13, and 14.), those in which at least one fish survived 

 beyond 7 hours, were also sampled for pH determinations 7 to 

 7z hours after beginning the study. During this 3l2-hour experi- 

 ment the room temperature varied from 20 to 24.5° C. 



Only one of the 32 fish subjected to initially bacteria-free 

 cultures survived the 3l2"-hour test period; all except three 

 (C. variegatus ) died within 8 hours (Table 6). The lone fish 

 (£. variegatus ) surviving the experimental period succumbed about 

 30 minutes later. On the contrary, only one of the 21 fish 

 exposed to control materials of sea water and initially sterile 

 cultiire medi\im failed to survive the test period. This fish 

 (C. variegatus ) died after nearly 30 hours in culture medium. 

 The "death times" of M. cephalus , which varied from ^ to 4-3/4 hours, 

 were considerably less than those of the C. variegatus . 3-4 to nearly 

 32 hours. Fifty percent (I6) of the test fish in the bacteria- 

 free cultures died earlier than those (4) in the unialgal culture; 

 the "death times" in this culture were about 1-^ hours for M. cephalus 

 and 6^ and 6-3/4 hours for C. variegatus . The test fish survived 

 considerably longer in the non-aerated than in the aerated G. brevis 

 culture in one instance; in the other case the opposite occurred 

 although the differences of survival in the two types of cultures 

 were less marked. 



The bacterial co\ints of the initially bacteria-free Go brevis 

 cultures sampled before adding the fish varied from 250 to 20,000 

 per ml. The rather high initial bacterial counts are attributed 

 to the prolonged standing (5 days) of the distilled water in the 

 experimental containers while the aeration equipment was being 

 tested and adjusted. The coimts obtained from these cultures 

 following the death of the last fish in the container (5 to 8 



22 



