distilled water all showed red branchial color- 

 ing before the final stained feeding and several 

 had accepted various degrees of abdominal 

 staining. Three died within 7 days. There was 

 irregular retention of abdominal coloring but 

 the bright-red branchial concentration showed 

 no indication of fading through 79 days following 

 the final stained feeding. An identical test on 

 II large shrimp produced similar results. 

 Three individuals surviving 65 days after the 

 final stained feeding all showed bright-red 

 branchiae . 



Twenty-five shrimp were given three 

 feedings stained with a 2 -percent solution, as 

 above, which had been warmed and filtered. 

 With the exception of two individuals which had 

 apparently not accepted stained food, all showed 

 red branchial coloring before the final stained 

 feeding. Of 7 shrimp surviving 183 days, 6 

 showed distinctly red or pink branchiae and one 

 showed no evidence of abnormal coloring. 



Fifty shrimp were given feedings stained 

 with a 1 -percent solution prepared with 45 ml. 

 of distilled water and 5 ml. of sea water . The 

 majority showed red to pink branchial coloring 

 after three feedings and several showed general 

 pink coloring. After the fifth feeding, the 2 

 most deeply stained individuals were isolated 

 and subsequently given normal food; those re- 

 maining were given four additional stained 

 feedings . Since no difference could be detected 

 in intensity of coloring, the two groups were 

 again combined 24 days after the final stained 

 feeding. Seven shrimp remaining after 127 days 

 all showed bright -red branchiae. Since can- 

 nibalism was high, it was impossible to deter- 

 mine differences in mortality between the 

 five -feeding and nine -feeding groups. 



Fifteen small shrimp were given eight 

 feedings stained as for the preceding experiment. 

 The majority showed red branchial concentration 

 following the third feeding and this held fast in 

 the six individuals surviving 127 days after the 

 final stained feeding. 



Immersion tests on two lots of 10 shrimp 

 in 0.2 -percent and 1 -percent solutions were un- 

 successful. In general all abnormal color faded 

 within 3 days. One shrimp accepted some red 



coloration in the branchiae, and this remained 

 fast for the 17-day duration of the experiment. 

 Several fruitless attempts were made to duplicate 

 branchial staining following immersion. 



Trypan Red (National Aniline) 



Twenty -five shrimp injected with a 

 filtered 1 -percent solution made up with 10 ml. 

 of distilled water and 90 ml. of sea water showed 

 an immediate pale -red branchial concentration 

 and several showed general pink coloration. 

 Initially this did not appear as bright as that pro- 

 duced by the Harleco product but it intensified 

 to a bright red within 8 days . Eventually, all 

 but one showed a diffuse pink coloring of the en- 

 tire cephalothorax, and abdominal staining was 

 retained when present. There was a high rate 

 of cannibalism following ecdysis, but a bright- 

 red color remained in the branchiae of four 

 shrimp surviving 79 days. 



The majority of 50 shrimp showed a 

 bright -red branchial color after two feedings 

 stained with a 2 -percent solution made up with 

 distilled water . This abnormal coloring was 

 evident in all after five feedings. Cannibalism 

 was great, but the branchial color remained fast 

 in 7 individuals througji 7 days following the final 

 stained feeding. 



Sixty shrimp were given five feedings 

 stained with a 2 -percent solution as above except 

 that it was warmed to facilitate dissolving of the 

 dry stain. Various degrees of abnormal coloring 

 from a pale -pink tinting of the branchiae to a deep- 

 red general coloration were observed following 

 the third stained feeding. Six shrimp, all with 

 the general coloration, died within 5 days, and 

 on the fifth day two individuals with similar color 

 exhibited a loss of equilibrium as noted previously. 

 One of these died within 3 days, while the other 

 survived 27 days and shed once without recover- 

 ing normal balance. Again cannibalism was high, 

 and after 58 days the 10 individuals remaining all 

 retained bright -red branchiae. 



Of 25 small shrimp given two feedings 

 stained as above, all but 4, which had apparently 

 not eaten, showed bright -red branchiae. Two 

 died within 6 days. There was no general stain- 

 ing, and no loss of equilibrium was observed. 



16 



