same observation tank as the stained shrimp. 

 A further check on experimental mortality was 

 provided by what might be termed the natural 

 mortality within the storage system. This is 

 the total mortality of nonexperimental shrimp 

 and was estimated to average about 15 percent 

 a week. 



EXPERIMENTS 



blue -green. Abdominal fading and cephalothor- 

 acic concentration was evident within 24 hours 

 and complete within 72 hours. Although there 

 was some fading, the stain remained through at 

 least one ecdysis and a pale -green color was 

 retained by the one shrimp surviving through 

 160 days. Though readily apparent to a careful 

 observer, the color was not sufficiently distinct 

 for field use . 



Each stain, with the exception of four 

 that proved insufficiently soluble in aqueous 

 solution, was tested by at least one of the three 

 staining techniques and frequently in a number 

 of concentrations and solvents . The num ber 

 of individuals used in each test ranged from 5 

 to 60. Of the 30 stains tested, 26 were found 

 unsatisfactory as shrimp -marking agents. A 

 summary of experiments with these unsuccess- 

 ful stains is presented in table 2. Tests involving 

 stains that are considered suitable shrimp- 

 marking agents are treated in some detail below. 

 The products of two manufacturers aie com- 

 pared in three of these stains. 



Fast Green FCF (Harleco ) 



Four injection experim ents were com- 

 pleted using this stain in concentrations of 0.75, 

 I.O, and 8.0 percent. Each solution was pre- 

 pared with sea water. Ten shrimp irtjected 

 with a 0.75 -percent solution showed an immed- 

 iate pale -green general coloration. Fading 

 from the abdominal region and simultaneous 

 concentration in the cephalothorax, especially 

 in the branchiae, was evident within 5 hours. 

 Coloring was pale, however, and within 3 days 

 it was not sufficiently obvious for identification 

 purposes. 



There was an immediate general blue to 

 blue -green coloration in 2 lots of 15 and 20 

 shrimp injected with the 1 -percent solution. 

 Abdominal fading was rapid, and the stain was 

 usually concentrated in the heart and branchiae 

 within 72 hours. Some fading was evident, but 

 a pale -green color was retained in the branchiae 

 of 2 shrimp remaining after 84 days. This col- 

 oration had remained fast through at least one 

 ecdysis. 



Fifteen shrimp injected with an 8 per- 

 cent solution were immediately colored a deep 



Ten shrimp were immersed for 15 min- 

 utes in a 0.75 -percent solution made up with 

 sea water. One shrimp died within 8 hours. 

 There was some slight stain acceptance in the 

 anterior digestive tract, branchiae and in irregu- 

 lar areas of the abdominal exoskeleton . Loss 

 of abdominal color was complete within 24 hours. 

 Rapid fading progressed and after 6 days only a 

 very light green tint was detectable in 2 of the 

 remaining 9 shrimp. 



Fifteen shrimp were given three feedings 

 stained with an 8 -percent solution prepared with 

 sea water. Stomach and digestive tract were 

 stained a moderate to deep blue which persisted 

 for 8 days after the final stained feeding. There- 

 after, fading was relatively rapid with only a 

 trace of abnormal coloration remaining in 13 

 days. 



Fast Green FCF (National Aniline) 



Two injection experiments were completed. 

 Fifteen shrimp injected with a 1 -percent solution 

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

 of sea water showed an immediate general blue- 

 green coloration. One died within 18 hours. 

 Except for a green spot at the injection site, 

 color was rapidly concentrated in the cephalothor- 

 ax. General cephalothoracic tinting and the spot 

 at the injection site faded slowly, but coloring in 

 the branchiae and heart remained fast for 120 

 days and through at least one ecdysis. The color 

 was very distinctive and could be readily detected 

 by even a casual observer. 



Twenty shrimp were injected with a 1- 

 percent solution m ade up with an unknown solvent. 

 this solution was supplied by Dr. Winston Menzel, 

 and was the same as that employed in his experi- 

 ments (Menzel, 1955). As usual with Fast Green 

 FCF there was rapid general green to blue -green 

 coloration with subsequent abdominal fading 



