Joydev Maity

Parasitic prevalences in fresh water prawn Macrobrachium rosenbergii in north and south 24 Parganas districts of West Bengal

The occurrence of different freshwater prawn (Macrobrachium rosenbergii) parasites, found during the period from April to August 2007, was investigated in different freshwater wetlands of north and south 24 Parganas districts of West Bengal state in India. Eleven parasites - Zoothamnium, Epistylis, Gregarina, Amphileptus, Dileptus, Myxobolus, Chilodonella, Balladyna, Gozia, Rhabdochona, Indocucullanus, Procamallanus and Cucullanus - were found after examining 1,000 specimens of Macrobrachium rosenbergii of different-sized groups. The highest prevalence of the parasites was recorded in the size group of 81-85 mm and 136-140 mm. The intensity of ectoparasitic infection was observed to be high with an increase in size. The gills and the surface of the body were mostly infected. Endoparasites were found in the intestinal part, and mostly due to poor raw foods given to the prawns as their diets. The parasites get more shelter and space for them. The highest intensity of those parasites was found in the month of August due to favourable autumnal conditions, with little rain and favourable breeding time of the parasites. Stressed and weak prawns are more vulnerable to infestation under adverse environmental conditions.

The use of antibiotics and disinfectants in the freshwater prawn (Macrobrachium rosenbergii) farms of north and south 24 Parganas districts of West Bengal

The freshwater prawn (Macrobrachium rosenbergii) farms and hatcheries of north and south 24 Parganas districts in West Bengal were surveyed for the details of antibiotics and disinfectants used for controlling the prawn diseases and pathogens. During the survey, 4antibiotics and four 4disinfectants were found to be used commonly by the farmers during a 12-month period of study. The chemicals used in the culture systems as antibiotics or disinfectants for the culture water, tanks, other utensils, and others have serious health hazards for both the cultured prawns and human beings. The study also indicates no herbal medicines, and probiotics are being used in prawn farms.