within 3 days . A green spot at the injection 

 site was retained for varying periods up to 53 

 days . The green staining of the branchiae and 

 cephalothorax showed some gradual fading, but 

 it was retained through at least one ecdysis 

 and remained very evident in the four shrimp 

 surviving after 84 days. 



Niagara Sky Blue 6B 



Fourteen shrimp were injected with a 

 1 -percent solution made up with 10 ml. of dis- 

 tilled water and 90 ml. of sea water. Immed- 

 iate coloration ranged from an overall medium 

 to a blue spot at the injection site; all showed 

 some branchial concentration. Three shrimp 

 died within 4 days . Gradual abdominal fading 

 was evident, and staining was confined to a 

 blue coloring of the branchiae and heart in 37 

 days . After 103 days, three surviving shrimp 

 showed well-defined dark-blue coloration of 

 these areas. In a similar test on 30 shrimp, 

 the results were generally the same. Three 

 shrimp died in 3 days; cannibalism was high 

 and only four shrimp survived after 52 days. 



Twenty -five shrimp were given 6 feed- 

 ings stained with a 1 -percent solution as above. 

 By the third feeding there was a dark -blue col- 

 oration of the stomach and digestive tract, and 

 several showed a poorly defined pale blue- 

 green in the branchial region. One shrimp 

 showed a bright blue -green staining of the bran- 

 chiae which was retained until termination of 

 the test 26 days after the initial stained feeding. 

 Examination of casts showed that much of the 

 branchial coloration was lost at ecdysis. 



Trypan Blue (Harleco) 



Ten shrimp were injected with a 1 -per- 

 cent solution prepared with 5 ml. of distilled 

 water and 95 ml. of sea water. This resulted 

 in pale -blue coloring of the branchiae and at 

 the injection site; several showed an overall 

 bluish tint. This initial staining was not spec- 

 tacular and at first appeared to be insufficiently 

 vivid for identification purposes. However, 

 within 24 hours a dark -blue concentration was 

 evident in the branchiae. Although there was 

 some tendency to fade to a dark blue -grey in 

 about 30 days, this color remained fast and was 

 readily observed in two individuals surviving 



through 141 days. Staining remained through 

 at least two shedding cycles. 



Among 20 shrimp given injections aver- 

 aging 0.05 cc. of a similar solution, several 

 showed signs of weakness and one died within 

 8 hours. The remainder recovered and showed 

 a moderate to dark blue in the injection area; 

 branchial and abdominal tinting occurred in 

 several. There was a dark -blue to blue -green 

 concentration in the branchiae within 55 hours 

 with simultaneous fading from other areas . Of 

 the three shrimp remaining through 179 days, 

 all retained dark -blue branchiae and two showed 

 a bluish tint at the injection site. 



Of 15 shrimp injected with a 1 -percent 

 solution made up with 10 ml. of distilled water 

 and 90 ml. of sea water, 3 died within 5 minutes 

 and 5 within 24 hours. This is presumed to have 

 resulted from too great an injection. Owing to 

 the initial absence of bright coloration, there is 

 a tendency to overinject when using this stain. 

 A general dark -blue branchial concentration 

 resulted within 24 hours, and this remained dis- 

 tinct in the two shrimp surviving through 220 

 days. 



Food acceptance was poor among 10 

 shrimp given three feedings stained with a 1 - 

 percent solution prepared with distilled water. 

 The digestive tract retained a pale bluish tint 

 unsatisfactory for identification purposes. 



Five shrimp were immersed for 15 min- 

 utes in a 0.4 -percent solution made up with 10 ml. 

 of distilled water and 990 ml. of sea water. This 

 resulted in an indistinct tinting of the cephalo- 

 thorax, but no evidence of abnormal coloration 

 could be seen after 24 hours. 



Trypan Blue (National Aniline ) 



Twenty- six shrimp were given injections 

 averaging 0.06 cc. of a 1 -percent solution made 

 up with 10 ml. of distilled water and 90 ml. of 

 sea water. This stain was less soluble in sea 

 water than the Harleco product, and the solution 

 was filtered before use. Immediate coloration 

 was detectable only at the injection site, in the 

 dorsal abdominal artery, and in a pale tinting 

 3f the branchiae. Within 24 hours there was a 

 general branchial concentration, and several 



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