First occurrence of the eel parasite Paraquimperia tenerrima in lake Balaton, Hungary

The parasite fauna of the eel has been studied regularly since the first imported eels were introduced to Lake Balaton in 1963. Over a long period of time no important parasitic infections were recorded. However, the importance of nematode infections has increased since 1991, when the pathogenic nematode Anguillicola crassus was first detected and intensive eel mortalities started to occur. This paper reports on the first occurrence of Paraquimperia tenerrima, a small nematode infecting the gut of the eel. Paraquimperia tenerrima is a common parasite in rivers of several European countries. Due to the small size and the low prevalence of the worm its pathogenic effect upon eels seems to be negligible in Lake Balaton

Paratenic hosts for the parasitic nematode Anguillicola crassus in Lake Balaton, Hungary

A 1 yr study was conducted to determine which fish species may play a role in the life cycle of Anguillicola crassus in various habitats of Lake Balaton, Hungary. The prevalence and intensity of the larval infection of fish species acting as paratenic hosts was studied, and observations were made on the types of paratenic host reactions against larvae. With the exception of 1 species, all 20 fish species were infected by A. crassus larvae; however, the prevalence and intensity of infection varied widely. Six species (asp, white bream, Chinese rasbora, pike, river goby, European catfish), hitherto unreported as paratenic hosts, also proved to be infected by larvae in Lake Balaton. Of the 13 fish species examined in large numbers, ruffe and European catfish showed the highest prevalence of infection (100 %), followed by river goby (83 %), white bream (79 %) and bleak (68 %). Of these 13 fish species, ruffe showed the highest intensity of infection by live larvae (mean intensity: 39.3 3rd stage larvae, L3), followed by European catfish (mean number of live larvae: 26.9) and river goby (mean number of live larvae: 9.1). The mean number of live L3 in bleak, a species regarded as the principal food source for eels, was 4.1. Specimens containing only dead or both dead and live larvae were much more common in cyprinid fishes than in species belonging to other taxonomical entities. In these fish, the process of encapsulation and subsequent necrosis of live larvae could also be observed. With knowledge of the feeding habits of eels, it appears that bleak play the most important role in the transmission of anguillicolosis. Other intensively infected fish species (e.g. ruffe) may also contribute to massive infection of individual eels, even if they have a lower share in the eels' food structure

Goussia trichogasteri n. sp. (Apicomplexa: Eimenidae) infecting the aquarium-cultured golden gourami Trichogaster trichopterus trichopterus

Goussia trichogasteri n. sp. is described from the gut of the aquarium fish Trichogaster trichopterus trichopterus. Gamogonic stages develop epicellularly in the gut epithelium. Oocysts are shed in early stage of sporulation. Sporulated oocysts are characterised by having centrally locating oocyst residua. The whole development of the species takes place in the aquarium

Praziquantel (Droncit) is effective against diplostomosis of grasscarp Ctenopharyngodon idella and silver carp Hypophthalmichthys molitrix

In laboratory experiments praziquantel (Droncit) effectively destroyed metacercariae of Diplostomum spathaceum (s. l.) parasitizing the eye lens of grasscarp Ctenopharyngodon idella and silver carp Hypophthalmichthys molitrix. A single treatment with Droncit fed at a dose of 330 mg kg^-1 body mass showed 100% efficacy against metacercariae parasitizing grasscarp. A similar, complete parasiticidal efficacy was achieved when infected grasscarp and silver carp specimens were exposed to a solution containing 1 mg praziquantel l^-1 for at least 90 h. Using shorter exposures (20 min to 1 h) but elevated praziquantel doses (10 to 100 mg l^-1), some parasites survived but even here the intensity effect reached 67 to 97%

An unusual case of disease in pet fish stocks caused by Coleps sp. (Protozoa: Kinetoflagminophorea)

In some stocks of fry of 3 aquarium fish species, Schulz's corydoras Corydoras schultzei, tiger barb Barbus tetrazona and black telescope eye goldfish Carassius auratus, 20 to 90 % mortality occurred. The mortality was caused by a ciliate protozoan which did not resemble any of the known fish ectoparasites. The deaths occurred in fry kept in densely populated aquaria. The protozoans were attached to the epithelium with their cytostoma and often covered the body surface in large masses. The protozoan was identified as a Coleps sp., previously known only as a coprophagous species or a predator of protozoans. This is the first report of losses caused by a Coleps sp. in fish fry