Behavioral and Growth Characteristics of the Crustacean Species Macrobrachium macrobrachion (Herklots 1851) (Decapoda: Palaemonidae) with Special Reference to Cannibalism

Abstract

This study investigates the behavioral characteristics of the crustacean Macrobrachium macrobrachion in view of their cannibalistic tendencies and growth rates. Seventy (70) prawns comprising of individual groups representing adult / post larvae groups of prawns were stocked in hapas in the following categories: adult males/females (5/5), 10 -adult females only, 10- adult males only, mixed males and females post (5/5), 10- adult females / 10 post larvae, 10- adult males/ 10 post larvae and 10 post larvae only. These animals were stocked in their triplicates and studied for fifty six (56) days. M. macrobrachion is nocturnal, and diurnally, they hide in shelters sneaking out to eat when food is available. Cannibalism was high in all the groups resulting in survival rates of 40%. Growth rates of 0.03 mgd-1 were not significant (P> 0.001) in adult male/female, adult male, adult female and adult male /post larvae categories respectively. Growth rates of 0.07 gmd-1, 0.05 gmd-1 were calculated from the groups that hosted adult female and the post-larval. Prawns in the mixed adults/the post larvae group exhibited the least growth rate of 0.02 gmd-1. Exuviate were found in the hapas indicating that animals were eaten during molting or that they were eaten up during the process of molting. This observation suggests that cannibalism was most prevalent among the latter categories than the former probably associated with nocturnal activities .Most individuals were found with single pleopods or none at all indicating situations associated with fight or aggression. The paper concludes with management strategies for the culture of crustaceans in captivity.