Background. Sturgeons have long been extinct in Polish inland waters. A substantial effort has recently been put into their restitution, covering the drainage areas of two major Polish rivers, the Oder and the Vistula. The stocked fishes are clinically healthy, but very little is known about their potential to transmit viral diseases including koi herpes virus (KHV) to healthy fishes of other species, which may pose a threat to the disease-free zones. This study was intended to determine if sturgeons could be asymptomatic carriers of KHV. Materials and Methods. A total of 29 sturgeons (two species; length 8-37 cm) originating from fish farms in northern Poland with a known KHV history in common carp or koi in the area were examined: 15 Russian sturgeons, Acipenser gueldenstaedtii, with clinical signs of a disease and 14 asymptomatic Atlantic sturgeons, A. oxyrinchus. The former were sent to the laboratory alive while the latter were sent fixed in ethanol. As it is required for detection of a latent KHV infection in acipenserids, two independent procedures were applied. The preliminary results were obtained using PCR. Those findings were subsequently confirmation by nested PCR. The latter procedure consists of sequence analysis of PCR products and direct detection of KHV infected cells in tissue materials by in-situ hybridization on nucleic acid level or indirect immunofluorescence on KHV protein level. Results. KHV genome parts were found in nine Russian sturgeons and four Atlantic sturgeons. Comparison of PCR results obtained from three primer pairs used for KHV diagnostic in sturgeon showed that those designed by Bercovier et al. were most sensitive and robust for this purpose. In order to confirm the presence of viral particles the most useful method was in-situ hybridization (ISH), allowing the detection of KHV in gill samples obtained from live sturgeons.Conclusion. This preliminary study shows that sturgeons can be carriers of KHV. Therefore a viral diagnostics is highly recommended not only for sturgeons obtained from the environment but also for fertilized eggs, fry, and fish intended for re-stocking measurements of inland waters.

Nine species-specific microsatellites were used to characterize 792 tench, Tinca tinca (L.), from 21 wild and cultured populations. Seven loci were polymorphic expressing four to 22 alleles. A Spanish cultured strain was homozygous at all loci for all individuals studied. Low variability was also observed in a wild population from Sapanca Lake, Turkey and a Chinese cultured strain. In contrast, the highest variabilities were found in wild tench from lake Felchowsee (average number of alleles), and the cultured strain from Königswartha (average heterozygosity), both from Germany. Genetic differentiation between populations was moderate to high. The smallest genetic distances were found between the geographically most distant populations. A NeighborJoining tree showed only two major clades consisting of 4 and 17 populations, respectively. Within the smaller clade the Turkish wild and Spanish and Chinese cultured tench formed a sub-cluster with 100% bootstrap support. Possible reasons for the latter unexpected grouping are discussed.

Homogeneous background (age, sex, genetic lineage, culture conditions) was created to clearly demonstrate the impact of the tested dietary treatments. No feeds optimized for the rearing of the tench (Tinca tinca L. 1758) are available. Feeds are formulated to increase the growth rate or eliminate skeletal deformations. With the increasing prices of the basic components, fish meal (FM) and fish oil, poultry by‐product meal (PBM) can be used. The aim of the study was to evaluate the effects of substitution of FM with PBM on the tench blood parameters, body composition and structure of skeletal muscles. Cage‐reared female tenches (325 ± 18 g) were fed for 86 days with five types of feeds with 0% (control), 25.7%, 48.6%, 71.4% and 100% substitution of FM with PBM. No significant differences between the formulations were reported for weight, total length, fillet weight, visceral, liver, gonado‐somatic, proximate composition and biochemical blood parameters. However, significant differences were found in the fillet profiles of fatty acids—an increase in the PBM content correlated with an increase in saturated and monounsaturated fatty acids and a decrease in n‐3 PUFA and, generally, n‐6 PUFA. Significant differences were also observed in, for example, the content of intramuscular fatty tissue and the level of organ lipidosis between the control variant (0% PBM) and that with 100% substitution. A sensory assessment indicated a higher gustatory value of the fillets in the case of feeds with 48.6% and 71.4% substitution.

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Barbosa et al. (2020). Enriched feeds with iodine and selenium from natural and sustainable sources to modulate farmed gilthead seabream (Sparus aurata) and common carp (Cyprinus carpio) fillets elemental nutritional value.

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