Evaluation of a visible implant fluorescent elastomer internal tag in juvenile freshwater prawn Macrobrachium rosenbergii (de Man)

The suitability of an internal tag -visible implant fluorescent elastomer tag (VIE) as a method to identify juveniles of Macrobrachium rosenbergii (initial mean weightpSE 1.25p0.05 g) was evaluated in the present study. Four fluorescent colours (red, orange, yellow and green) were tested for tag retention and readability during 100 days of rearing in an out-door rearing facility. Effect of tagging on growth and survival of the prawns was also evaluated. Tag retention (%) ranged from 98 to 100%. All the tags were visible to the naked eye till the completion of the experiment. Red tags were most visible followed by orange, green and yellow in that order. Final survival ranged between 74.9 and 90.4% in different groups. Survival in control prawns was lower than some of the tagged prawns (green, orange), indicating that tagging with VIE tag had no effect on survival of these prawns. No significant differences (P<0.05) in growth could be observed between the tagged prawns and untagged controls. These results indicate that M. rosenbergii can be effectively tagged with VIE tags, and it can be used as batch tag to identify families in a selective breeding programme.