ABSTRACT 



To determine the effectiveness of biological stains as marking agents 

 for the commercial shrimp Penaeus setiferus , P^. aztecus , and^. duorarum, 

 experiments were conducted on captive shrimp held in storage tanks and 

 aquariums supplied with circulating sea water. Some 26 stains were tested 

 by immersion, injection, and feeding. Staining by immersion proved consistent- 

 ly unsuccessful. Distinctive and fast abnormal coloration has been induced by 

 injection with Fast Green FCF (National Aniline), Niagara Sky Blue 6B, Trypan 

 Blue, and Trypan Red. Feeding with mullet ( Mugil cephalus ) previously stained 

 with Trypan Red also results in abnormal coloration suitable for identification. 

 The feeding technique constitutes a satisfactory method for marking shrimp 

 under 80 mm . in length. Whether these stains will prove equally fast under 

 natural conditions must be determined by field experiments. 



