During a survey on
infection of pond-cultured common carp in Syria three
spp. were found.
infected the gill arteries, forming large elongated plasmodia in the gill filaments. The plasmodia of
were located in the gill arches at the base of the filaments. Elongated filiform plasmodia of
were found in the blood vessels of the brain. Despite the common occurrence of the above parasites, no disease symptoms were observed in the infected fish specimens. This is the first report on myxosporean infection of fish from Syrian waters.
The aim of our study was to survey the geosmin (GSM) and 2-methylisoborneol (MIB) concentrations of the sediment and that of common carp (Cyprinus carpio) flesh in three different Hungarian fish farms (clayey, marshy, and sodic ponds).
Results showed that the concentrations of off-flavour compounds of the sediment and fish fillets were related to the natural environment. The GSM concentration of bottom soil samples was higher, than MIB in each fish farm. Both off-flavour compounds were the highest in the marshy fish pond and the lowest in the sodic pond. In case of fish flesh, significant differences were found between the farms in GSM level and fat content. In the fish flesh the same tendency was found as in the sediments, but surprisingly, MIB concentration was higher in the fillets, referring to accumulation.
Four important Hungarian common carp (Cyprinus carpio L.) breeds (Attala mirror, Attala scaled, Hortobágy scaled and Szeged mirror) harvested from different fish farms were analysed in this study. Main body indices, slaughter characteristics, fillet fat content, and conventional fish flesh quality characteristics were measured and compared. The slaughter value of the mirror strains tended to exceed that of the scaled type carps. For the calculated body indices (profile, cross-sectional, head and tail index) the influence of strain was statistically proven. Fillet fat content was significantly (P<0.01) affected by strains/ponds. The pH value of the fillet was significantly influenced by the strain as a fixed factor. Large, strain dependent variability was proven in fat content besides identical fillet dry matter contents. It was assumed that culture conditions and strain largely influence and lead to a marked variability of the body composition and flesh quality of the most important Hungarian fish species.
In this study, nine anticoccidial drugs commonly used in poultry were tested for efficacy for the prevention and treatment of
(Apicomplexa) infection in common carp (
L.). To establish experimental infection with
, paratenic host oligochaetes of the genera
were infected with oocysts, and laboratory-cultured parasite-free common carp fingerlings were infected by feeding to them oligochaetes containing sporozoites. The anticoccidial drugs (amprolium, narasin, maduramicin, salinomycin Na, lasalocid Na, diclazuril, robenidine HCl, monensin Na and toltrazuril), mixed in the food of the fish in a dose of 200 mg/kg, were fed for 12 days. Common carp fingerlings fed diclazuril, lasalocid, robenidine HCl or maduramicin and killed on day 14 after exposure were free from infection, while other groups treated with amprolium, toltrazuril, monensin Na, narasin or salinomycin Na harboured oocysts in the mucus and epithelium of the gut.
One of the main obstacles in freshwater aquaculture is the parasitic ciliate Ichthyophthirius multifiliis (Ich), the causative agent of white spot disease. The use of immunostimulants as feed additives may be a promising approach to control Ich infection. In the present study, we tested the prophylactic effect of orally administered β-1,3/1,6-glucan and propolis extract E50 against Ich infection in common carp. In total, 122 fish were separated into three experimental groups fed with a control, 3% β-glucan and 1% propolis diet for 40 consecutive days, respectively. On day 40, 16 fish per group were individually exposed to Ich theronts and the number of trophonts was counted 5 days post exposure. Relative gene expression of interleukin 1-β (IL-1-β) in common carp liver was examined by qPCR. Compared to control, the mean infection intensity was lower in the β-glucan- and propolis-fed groups; however, the difference was not statistically significant. The relative expression of IL-1-β significantly decreased in the propolis-fed group at day 10. In the β-glucan-fed group, a significant IL-1-β decrease was detected at day 15 compared to control. Although the Ich infection intensity was slightly decreased in both treated groups, and IL-1-β was moderately down-regulated in the liver of common carp, our results suggest that the applied feeding regime is insufficient to prevent Ich outbreaks in common carp.
Secondary sexual characteristics such as softening and rounding of the abdomen as well as reddening and protrusion of the anal papilla and vent can be of help to breeders in selecting common carp (Cyprinus carpio) females prepared for propagation. To assess the reliability of this method, long-term data obtained on induced spawning of common carp at a large-scale fish hatchery were evaluated. The average spawning ratio of 2,620 females receiving hormonal injections was 79.8%. The average pseudogonadosomatic index (PGSI) calculated from data on the egg production of 2,086 females was 16.3 ± 5.87% (mean ± SD) for the same period. There was a correlation between fish weight and the time of induction determined by the breeder on the basis of external morphological characteristics. The similarity of the responses of females, including both spawning ratio and PGSI, among the different weight categories proved the reliability of this method for identification.
1 Introduction Commoncarp ( Cyprinus carpio L.) is an important fish of freshwater aquaculture ( Roy et al., 2020 ). In some countries of Europe, carp make up more than 80% of the total fish production ( Anton-Pardo et al., 2014 ). Traditional
During a general annual fish health survey in natural waters and ponds, epitheliocystis infections were recorded in fingerlings of two cyprinid fish species, the cultured common carp and the wild gibel carp. Benign and heavy infections were equally observed without mortality. In addition to the general health inspection of fish, histopathological examinations of infected gills and molecular biological investigations of separated epitheliocysts were performed. Epitheliocysts were formed both in the interlamellar epithelial cells and in the lamella-free multilayered epithelium of the gill filaments. At the early stage of infection darkstaining inclusion bodies densely stuffed with some pathogenic agents were located at the centre of the cell, while in a progressive stage of the process inclusion bodies within the host cells were disseminated in the cytoplasm and stained pale. Molecular studies demonstrated three different agents related to Neochlamydia, Protochlamydia and Piscichlamydia based on sequence analysis of short regions of the 16S rRNA gene. Among them, Piscichlamydia is a primary fish pathogen, while Neochlamydia and Protochlamydia mostly infect free-living amoebae but have adapted thoroughly to fish.
The weight of internal organs (swimbladder, kidney, liver, spleen) in relation to the body weight was studied in common carp fingerlings divided into three groups on the basis of swimbladder appearance and microscopic examination of the kidney. The fish had been collected from different Hungarian fish farms at the time when swimbladder inflammation (SBI) usually occurs (in July and August). The first group comprised fish with severe signs of SBI and massive renal sphaerosporosis, the second group consisted of fish with milder swimbladder changes and/or kidney infection by a low number of Sphaerospora renicola, while the third group was constituted by infection-free common carp fry. Statistical analysis of swimbladder, kidney, liver and spleen weight in relation to the body weight revealed that in the infected groups the internal organs were substantially enlarged. This suggests that in common carp fry with SBI the swimbladder changes are accompanied by reno-, hepato- and splenomegaly.