Four bass averaging 76 mm., in length were kept in each of 

 three aquaria, the water temperature averaging i>U° F. The two 

 experimental groups receiving maggots treated with DDT in oil 

 (formula 2) ate A2 and 75 in one aay, while the control fish 

 devoirred 50 untreated larvae. All fish appeared normal sioc days 

 later. This experiment suggests that larger fish of this species 

 are less susceptible to DDT poisoning than smaller ones, 



Consumption by Smallmouth Black Bass of DDT-Sprayed Insects 



In a preliminary experiment, three aquaria were each stocked 

 with four smallmouth black bass (4.9 to 69 mm., in length). The 

 average temperature of the water in the aquaria was' 70° F. In 

 one aquariiim, the fish were- fed midge larvae sprayed with wettable 

 DDT (formula 1). One bass ate 20 larvae and died 16 hours later; 

 another consiomed 15, and died 2 days later, at which time, another 

 died that had not fed; vrtiile the largest fish (69 mm.,) consumed 

 90 larvae and was alive 12 days afterwards when the experiment was 

 concluded. 



Two bass ^each 54 mm., in length) in separate jars were fed 

 midge larvae sprayed with wettable DDT. The fish were then fasted. 

 One devoured 4.5 lai^ae in one afternoon and died about 6 days later; 

 the otiier took 73 larvae in 10 minutes, Ihis fish was active for the 

 following 6 days, then became sluggish for several days, and died 11 

 days after the large feeding. 



In another experiment, tnree smallmouth bass (70 to 79 mm.,) 

 were fed 5, 9, and 10 adult houseflies sprayed with wettable DDT, 

 and a control was fed 11 untreated flies . The average temperatiire 

 of the water in the aquarium ^ars was 70° F. The bass that ate five 

 flies died in 5 days, whereas the others were healthy 10 days after 

 feeding. The fish that ate 9 treated adult flies was fed 14 un- 

 treated housefly larvae; it died 5 days later. The bass originally 

 given 11 untreated adult flies was fed 20 spr*ayed larvae, and was 

 alive 7 days later, when this experiment was discon^iinued. The other 

 bass originally fed 10 treated adult flies was fed 14 larvae treated 

 with DDT in oil (formula 2) at the same dosage, and died 6 days later. 



These experiments indicate tnat sma] Imoutn black bass sometimes 

 die from feeding on sprayed insects. It also showed that they could 

 gorge themselves on poisoned insects without dying. Observations 

 combined with the erratic results obtained in this and in certain 

 other experiments suggested that fish in poor condition were the most 

 susceptible to DDT poisoning. 



