The mixed phylogenetic origin of northern pike (Esox lucius Linnaeus 1758) populations in the Middle Danubian drainage.

Background: Pikes, members of genus Esox, are widespread freshwater predators of the northern hemisphere, and important sport fish also. From the Carpathian basin only one species, the northern pike (E. lucius) is noted.

Historical dispersal and host-switching formed the evolutionary history of a globally distributed multi-host parasite - The Ligula intestinalis species complex.

Studies on parasite biogeography and host spectrum provide insights into the processes driving parasite diversification. Global geographical distribution and a multi-host spectrum make the tapeworm Ligula intestinalis a promising model for studying both the vicariant and ecological modes of speciation in parasites. To understand the relative importance of host association and biogeography in the evolutionary history of this tapeworm, we analysed mtDNA and reduced-represented genomic SNP data for a total of 139 specimens collected from 18 fish-host genera across a distribution range representing 21 countries.

Comparison of the Genetic Structure of Invasive Bigheaded Carp ( spp.) Populations in Central-European Lacustrine and Riverine Habitats.

Bigheaded carps (bighead carp, , and silver carp, ) and their hybrids play an important ecological and economic role in their original habitat, while their introduced stocks may pose serious ecological risks. To address questions about the persistence and invasiveness of these fish, we need to better understand their population structures. The genetic structures of bigheaded carp populations inhabiting Lake Balaton and the Tisza River were examined with ten microsatellite markers and a mitochondrial DNA marker (COI).

Increased spatial resolution of sampling in the Carpathian basin helps to understand the phylogeny of central European stream-dwelling gudgeons.

Background: Phylogenetic studies of widespread European fish species often do not completely cover their entire distribution area, and some areas are often excluded from analyses than others. For example, Carpathian stocks are often omitted from these surveys or are under-represented in the samples. However, this area served as an extra-Mediterranean refugia for many species; therefore, it is assumed that fish stocks here may show special phylogenetic features.

New record of metacercariae of the North American Posthodiplostomum centrarchi (Digenea, Diplostomidae) in pumpkinseed (Lepomis gibbosus) in Hungary.

Two species of the genus Posthodiplostomum (Digenea: Diplostomatidae) (Posthodiplostomum brevicaudatum Nordmann, 1832 and Posthodiplostomum cuticola Nordmann, 1832) are known as parasites of Hungarian native fishes. Metacercariae of P. cuticola are widespread in Europe and cause black spot disease.

Microcystis Chemotype Diversity in the Alimentary Tract of Bigheaded Carp.

Most cyanobacterial organisms included in the genus can produce a wide repertoire of secondary metabolites. In the mid-2010s, summer cyanobacterial blooms of sp. occurred regularly in Lake Balaton.

Repeatability, Reproducibility, Separative Power and Subjectivity of Different Fish Morphometric Analysis Methods.

We compared the repeatability, reproducibility (intra- and inter-measurer similarity), separative power and subjectivity (measurer effect on results) of four morphometric methods frequently used in ichthyological research, the "traditional" caliper-based (TRA) and truss-network (TRU) distance methods and two geometric methods that compare landmark coordinates on the body (GMB) and scales (GMS). In each case, measurements were performed three times by three measurers on the same specimen of three common cyprinid species (roach Rutilus rutilus (Linnaeus, 1758), bleak Alburnus alburnus (Linnaeus, 1758) and Prussian carp Carassius gibelio (Bloch, 1782)) collected from three closely-situated sites in the Lake Balaton catchment (Hungary) in 2014. TRA measurements were made on conserved specimens using a digital caliper, while TRU, GMB and GMS measurements were undertaken on digital images of the bodies and scales.

Population Genetic Patterns of Threatened European Mudminnow (Umbra krameri Walbaum, 1792) in a Fragmented Landscape: Implications for Conservation Management.

The European mudminnow (Umbra krameri) is a Middle Danubian endemic fish species, which is characterised by isolated populations living mainly in artificial habitats in the centre of its range, in the Carpathian Basin. For their long term preservation, reliable information is needed about the structure of stocks and the level of isolation. The recent distribution pattern, and the population genetic structure within and among regions were investigated to designate the Evolutionary Significant, Conservation and Management Units (ESUs, CUs, MUs) and to explore the conservation biological value of the shrinking populations.