Histology of loose-shell affected Penaeus monodon

The loose-shell affected Penaeus monodon was studied for induced infection, recovery and histology under the laboratory condition and grow-out system. The maximum percentage of loose-shell affected animals was 23.3% in summer and 14.15% in winter culture ponds. Mortality pattern of experimentally infected animals varied with the mode of infection. The cumulative mortality reached 100% within 9 to 10 days through the water infection, 11 to 12 days through oral feeding, 12th day at 0.01 ml, 8th day in 0.05 ml and 4th day at 0.1 ml through the intramuscular injection. A marked recovery of loose-shell P. monodon fed with frozen clam, mussel meat at 12% of body weight daily was observed. The data suggested that improved survival, up to 64% shell recovery and 17 to 47.5% of weight gain in the case of clam meat experiment, and up to 66.6% shell recovery and 16.2 to 48.4% of weight gain in mussel meat experiment. The histology of the loose-shell-affected animals showed the presence of inclusion bodies, gill cuticle separated from the epithelial cells, degeneration of basement membrane in the gut.