A new report of argulus indicus (Crustacea: Branchiura) infestation in red tilapia (Oreochromis niloticus x Oreochromis mossambicus) in Thailand

Abstract

Argulus indicus (Crustacea: Branchiura), or the fish louse, is an external parasite in Phylum Arthropoda found on the skin, fin or gills of freshwater fish species. It is very flat with an oval or rounded carapace, two compound eyes, sucking mouthparts with a piercing stylet, and two suction cups it uses to attach to its host. Clinical signs in infected fishes include scratching on aquarium walls, erratic swimming and poor growth. It causes pathological changes due to direct tissue damage and secondary infections. In the present study, red tilapia (Oreochromis niloticus x Oreochromis mossambicus), with symptoms such as abnormal swimming or scratches on their skin, were collected from a cage culture at Klong Rapee-Phat, Nong-Seau District, Pathum-Thani Province in Thailand. The parasites collected from the skin and fins of infected red tilapia were identified as Argulus indicus. This is the first report of infection with A. indicus of red tilapia (O. niloticus x O. mossambicus) in Thailand.