Mass mortality of Nile tilapia caused by co-infection with Enterogyrus spp. (Monogenea: Ancyrocephalinae) and Aeromonas jandaei following transport stress

Monogenean infection of the internal organs is extremely rare when compared to external infections. This study describes mass mortality of Nile tilapia (Oreochromis niloticus L.) originating from co-infection with Enterogyrus spp. and Aeromonas jandaei following transport stress. The first fish deaths occurred on day 1 post-transport, while cumulative mortality reached approximately 90% by day 10 post-stocking. An atypical amount of pale (whitish) faeces floating on the surface of the water as well as typical clinical signs of motile Aeromonas septicemia, were reported. Adult monogeneans and countless eggs of monogeneans were found in the stomachs and the intestines of both moribund and dead fish, respectively. Two strains of A. jandaei were isolated from the kidneys. Scanning electron microscope microphotographs of the stomach revealed the presence of numerous monogeneans penetrating deep into the gastric tissue, and diffuse lesions filled with bacilliform bacteria. This is the first report of co-infection by Enterogyrus spp. and A. jandaei in Nile tilapia and the first report of E. coronatus, E. foratus, and E. malbergi parasitizing tilapia in Brazil. These findings indicate that synergic co-infection by Monogenean stomach parasites (E. coronatus, E. foratus, and E. malbergi) and A. jandaei may induce high mortalities in tilapia following transport stress.

Prevalence of Monogenean Helminth Ectoparasites on Catfish (Clarias gariepinus) Culture Ponds in Laban Village, Menganti District, Gresik Regency, East Java Province

The aims of this study are to know the prevalence of monogenean helminth ecto-parasites infection on catfish culture, to know determine the number of monogenean infection on 100 samples consists of 1 and 3 months old of catfish. This study was conducted on May to June, 2011 in catfish culture ponds, Laban Village Menganti District and Gresik Regency, East Java Province. The methods were used in this research were skin and gill scrapping. The data were analyzed by using chi square test with SPSS program version 18.0 for windows. The results showed that prevalence of monogenean in catfish culture ponds, Laban Village Menganti District Gresik Regency, East Java Province was 32%. The highest infection was in the young catfish compared with the older ones with percentage of 23% and 9% respectively and based on chi square test showed that there were a very significantly differences (p < 0.01).

Occurrence and morphogenetic characteristics of Gyrodactylus (Monogenea: Gyrodactylidae) from a rainbow trout farm (Lake Ladoga, Russia)

Gyrodactylus parasite infected juveniles on rainbow trout Oncorhynchus mykiss (Walbaum, 1792) from a fish farm in Lake Ladoga were investigated. The observed cases of infection in fish featured a high prevalence, when almost all of the fish were infected. However, if an outbreak of the monogenean infection is observed in spring, the intensity of the infection may be low, and when the infection occurs in the ice-covered period (late autumn - winter), the number of parasites on the fins of a single fish may exceed 3000 specimens. Molecular identification of the parasite demonstrated that the infecting clone was identical with rainbow trout specific strain of Gyrodactylus salaris RBT widely spread in Northern Europe, but a small proportion of the parasites were the hybrid clone Gyrodactylus pomeraniae x G. lavareti. Morphological variations of hooks and other opisthaptor parts in the monogenean Gyrodactylus depending on the intensity of infection in rainbow trout were demonstrated.

Benedenia epinepheli (Yamaguti 1937), A Monogenean Parasite in Captive Broodstock of Grouper, Epinephelustauvina (Forskal)

Grouper (Epinephelus spp.) is one of the most economically important cultured marine fish in Asia, particularly in Thailand, Malaysia, Philippines, Singapore, Indonesia and Taiwan. Over 10 species of grouper fish have been cultured in the region. In India, greasy grouper fish, Epinephelus tauvina is gaining importance as a candidate species for marine and coastal aquaculture. A study conducted on wild and captive broodstock of grouper (size range, 15 - 40 cm; body weight 0.2 - 4 Kg) collected from sea near Chennai revealed infection with monogenean parasites in a large number of fishes (27%). The present communication is the summary of the prevalence, taxonomy and pathology of these infection encountered in E. tauvina and the containment strategies. Acute infection of ectoparasitic monogeneans, Benedenia sp. was observed in 19 wild grouper (E. tauvina) fish and 12 of the broodstock fish maintained in captivity. The parasite measured 2.05 - 3.29 x 0.66 - 1.33 mm and was found to infest the gills, fins and skin of the fish. Fishes with advanced infestation were characterized by erratic swimming behaviour and restlessness. The fish with severe infections had small focal haemorrhages on the body, which often resulted in secondary bacterial infection leading to the sloughing of the skin and excessive mucus secretion. A description of the parasite and its pathobiology is discussed. Successful treatment of monogenean infection was carried out by short bath treatment with 100 ppm formalin. Freshwater bath was found effective in dislodging the parasite from the fish. Hydrogen peroxide (150 ppm) bath was found to be effective but revival of parasite was observed after short bath.