trout) dislike the taste of the drug. Grovrth of rainbow trout did not 

 appear to be affected and brook trout showed marked retardation only 

 at the 10- and 15-gin. dosage rates. On the other hand, food consumption 

 was very poor and growth stopped in brown trout treated with sulfamerazine 

 at any rate. In 194-75 Outsell did find that a 10 gm. rate or more 

 slowed growth in fingerling brook trout but that little effect was 

 observed in rainbow trout even at the 15-gnio rate. 



Hemoglobin content and erythrocyte counts have been found to 

 increase in brown trout treated with sulfamerazine (Outsell and Snieszko 

 19/+9b). For fish treated at 5-, 10-, and 15-gm. rates^ the hemoglobin 

 content was 9.7., 9.4s and 8.9 gm. respectively. For control fish the 

 content for 100 cc. of blood was 7,0 gm. The level of hemoglobin for 

 fish treated at the 5-=gm. rate was significantly higher than that for 

 the 15-gm, rate but not so for 10-gm. rate. Erythrocyte counts made 

 after 42 or more days on brown trout showed mean counts per cubic mm. of 

 1,009,500 in the controls, 1,441,000 for the 5-gm. rate, 1,265,250 for 

 the 10-gm. rate, and 1,300,000 for the- 15-gm. rate. Significance was 

 shown only between the 5- and 10-gm. rate. 



Outsell and Snieszko (1949b) pointed out that the increase of 

 hemoglobin and of erythrocytes in fish treated with sulfamerazine may 

 have several explanations. It is possible that some infection causing a 

 moderate anemia was cured or greatly reduced by sulfamerazine therapy. 

 Another liypothesis is based on the finding that sulfonamides inhibit 

 respiratory enzymes (Altman 1946). It is possible that this action has 

 the same effect as a reduction in the supply of oxygen and like it 

 results in higher eiythrocyte and hemoglobin levels (Phillips et al 1947). 

 A final possibility is that sulfamerazine actually stimulates the 

 production of hemoglobin and erythrocytes in trout. 



Snieszko and Friddle (1951) have shown that increase in dosage 

 of sulfamerazine results in a proportional increase of tissue 

 concentration of this drug. Using brook trout ( Salvelinus f ontinalis ) 

 weighing about 23 gm. each, it was found that maximum tissue concentrations 

 were attained on about the sixth day. These were approximately 3.7 mg. 

 percent for a 10 mg. dosage per 100 gm. of trout per day, 6.9 mg. 

 percent for a 20 gm. rate, and 8.9 mg. percent for a 30 ing. rate. The 

 tissue concentration of sulfamerazine was also found to increase during 

 the first 4 days. It was then relatively uniform during the next 6 days 

 but dropped rapidly when the drug was eliminated from food on the 10th 

 day (to less than 0.25 mg. percent by the fourteenth day). 



Of eight sulfonamides administered to brook trout (S. f ontinalis ) , 

 Snieszko and Friddle (1951) found that sulfanilamide reached the 

 highest tissue concentration (S to 9 mg. percent). The concentration 

 began to drop after the ninth day regardless of continued treatment. 

 The reason for this is unknown. The tissue concentration of sulfamerazine 

 reached a somewhat lower level than that of sulfamethazine but the 



67 



