Status, occurrence, intensity and impact of Argulosis in different brood stock ponds

Abstract

Fish lice belonging to the genus Argulus, is a hazardous ectoparasite for the hatchery farmers. In order to understand the occurrence, intensity and impact of Argulosis on carp fishes, the present study was conducted in three Fish Seed Multiplication Farms (Hatcheries), such as Kashipur Farm, Gouranadi Farm and Ujirpur Farm at Barisal District, Bangladesh from November 2012 to April 2013. Highest infestation (79.17%) and intensity (41.34 per fish) of Argulus sp. were found in Ujirpur Hatchery, followed by those in Gouranadi (37.41% and 13.17 per fish) and Kashipur (17.11% and 10.91 per fish). Species-wise highest infestation (65.71%) and intensity (25.86 per fish) were found in Labeo rohita, followed by Cyprinus carpio (60.00% and 12.00 per fish) and the lowest in Cirrhinus mrigala (38.61% and 5.02 per fish). Sex-wise infestation and intensity of Argulus sp. were always higher in the female carps than male and in all ponds L. rohita had the highest rate of infestation than those in C. carpio and C. mrigala, and the most infested carps always were the females. Similar to the sex, length-wise highest prevalence and intensity of Argulosis were occurred in the largest size groups of carps and among them, the highest infestation was in L. rohita, followed by C. carpio and the lowest was in C. mrigala. The heavily infected fish experienced physical injury and showed abnormal swimming, and blood oozing from the fish caused red skin lesions and then secondary infection took place by bacteria (Aeromonas, Pseudomonas) and other parasites and fungi. Argulosis delayed the fish production and near about 15-30% production losses were occurred due to lower growth, survival and production of infected carps in captivity.