Effect of Papain on Unusual Behaviour of Fishes and Prawns

Abstract

This paper deals with an unusual behaviour of some fshes, prawns and shrimps reared in a nano pond of 26' í— 18' size, located in the homestead area at Santiniketan, Birbhum district, West Bengal. Water source of this mini-size pond was rain water and also from deep tube-well or well water during dry seasons. After rain fall water of this pond becomes turbid due to erosion of soil from the bank. Once a papaya plant of 6 months of age, having girth of 3" at base and 2" at the top and a length of 4' was cut into three pieces and was put in water of the pond during a sunny day at about 9 AM in the month of July 2012 to clear the turbidity of water. After 24 hrs, it was found that the water became clean and transparent. After 48 hrs at about 8 AM, the crustacean species, mainly the galda prawns were found to try to keep their head portion above the water at the edge of the pond, while most of the small shrimp species came near the bank and died after 3-4 hours. By this time the carp varieties of fishes appeared sluggish in nature whereas the Tilapia and the Nilentika showed normal behaviour. Thus, it seems that the papaya plant and/or its latex, containing papain can be utilized in limited doses to catch the prawn and shrimp species in an eco-friendly way, minimising the cost of catching without detriment to the health of shrimp-eaters.