Ing. Karel Halačka, CSc.

Position: grant funded researcher
Research topics: ichtyology
Department: Research facility Brno
Phone: +420 543 422 532

Research intersts

  • ecology, reproduction of fish, histochemistry and karyology,
  • study of silver crucian carp (Carassius auratus gibelio) polyploid complex and its dynamics on the territory of the Czech Republic,
  • reproduction of fishes, histology of their gonads and integumen,
  • conservation of endangered fish species.

Running Projects


Application of "top-down" biomanipulation to reduce eutrophication caused by agriculture in reservoirs (2016-2018)

Why and how animals abandon sex? On the causal role of hybridization in triggering asexual reproduction (2017-2019)

Finished Projects

Fish biodiversity in the Morava and Dyje confluence area – supporting and stabilization of rare and endangered species populations

Population and genetic structure of brown trout and grayling as groundwork for efficient management of fisheries in salmonid waters


1979-1983: undergraduate study - Mendel University of Agriculture and Forestry, Brno, specialization fishery. Thesis: Influence of aflatoxins contaminated food on fry carp.


  • 1985-1989: Ph.D. stay - Institute of Vertebrate Zoology, Department of Ichthyology, thesis: Histology, histochemistry and ultrastructure of fish epidermis.
  • 1989–present: Institute of Vertebrate Biology AS CR - reserach scientist.



Fedorčák J., Pekárik L., Halačka K., Šmiga Ľ., Manko P., Hajdú J., Vetešník L., Koščo J.: Microhabitat preferences of triploid Cobitis fish and diploid progenitors in two streams in Slovakia (Danube River Basin), Limnologica 69 (2018) 59-66.

Jurajda P., Roche K., Halačka K., Mrkvová M., Zukal J.: Winter activity of common bream (Abramis brama L.) in a European reservoir, Fisheries Management and Ecology 25 (2018) 163-171.


Fedorčák J., Koščo J., Halačka K., Manko P.: Growth differences in different biotypes of the hybrid complex of Cobitis elongatoides x Cobitis tanaitica (Actinopterygii: Cypriniformes: Cobitidae) in the Okna River (Danube River basin), Slovakia, Acta Ichthyologica et Piscatoria 47 (2017) 125-132.

Halačka K., Muška M., Mendel J., Vetešník L.: A newly discovered population of the Balkan spiny loach Sabanejewia balcanica (Karaman, 1922) in the River Jihlava, Czech Republic, Folia zoologica 66 (2017) 163-166.

Lusk S., Koščo J., Lusková V., Halačka K., Mendel J., Košúth P.: The nonindigenous fish Perccottus glenii in the Tisza River drainage, Eastern Slovakia – I. part: history of invasion, habitat associations and genetic characteristics (results up to the year 2006), Lampetra. Bulletin pro výzkum a ochranu biodiverzity vodních toků 8 (2017) 127-143.

Lusk S., Halačka K., Májsky J., Vetešník L., Mendel J.: Sekavčík balkánský (Sabanejewia balcanica) v České republice – minulost, současnost a budoucnost, Lampetra. Bulletin pro výzkum a ochranu biodiverzity vodních toků 8 (2017) 90-102.


Stierandová S., Vukic J., Vasil'eva E. D., Zogaris S., Shumka S., Halačka K., Vetešník L., Švátora M., Nowak M., Stefanov T., Koščo J., Mendel J.: A multilocus assessment of nuclear and mitochondrial sequence data elucidates phylogenetic relationships among European spirlins (Alburnoides, Cyprinidae), Molecular Phylogenetics and Evolution 94 (2016) 479-491.


Halačka K.: Differences in haematology and respiratory system morphology at three neogobiid species, Open Life Sciences 10 (2015) 514-520.

Halačka K., Kopp R., Klíma O., Mareš J.: Epidermis structure in the brook trout (Salvelinus fontinalis) and its Arctic char (Salvelinus alpinus) hybrid, Acta veterinaria Brno 84 (2015) 159-166.

Halačka K., Pekárik L.: Length-weight relationship of Cobitis elongatoides Heckel & Kner, 1858 from a pure diploid population in the Nová Říše Reservoir, Czech Republic, Journal of Applied Ichthyology 31 (2015) 562-564.

Šimková A., Vojtek L., Halačka K., Hyršl P., Vetešník L.: The effect of hybridization on fish physiology, immunity and blood biochemistry: A case study in hybridizing Cyprinus carpio and Carassius gibelio (Cyprinidae), Aquaculture 435 (2015) 381-389.

Šimková A., Hyršl P., Halačka K., Vetešník L.: Physiological and condition-related traits in the gynogenetic-sexual Carassius auratus complex: different investments promoting the coexistence of two reproductive forms?, BMC Evolutionary Biology 15 (2015) 154.


Vítek T., Halačka K., Bartoňová-Marešová E., Vetešník L., Spurný P.: Identification of natural hybrids between Cottus poecilopus, Heckel, 1837, and Cottus gobio, Linnaeus, 1758, at a hybrid zone on the Svratka River (Czech Republic), Journal of Applied Ichthyology 30 (2014) 102-108.


Vetešník L., Halačka K., Šimková A.: The effect of ploidy and temporal changes in the biochemical profile of gibel carp (Carassius gibelio): a cyprinid fish species with dual reproductive strategies, Fish Physiology and Biochemistry 39 (2013) 171-180.


Halačka K., Vítek T., Vetešník L., Spurný P.: Epidermis structure and blood parameter differences between sculpin Cottus gobio and Siberian sculpin Cottus poecilopus from the Morava watershed, Folia zoologica 61 (2012) 9-16.

Mendel J., Papoušek I., Marešová E., Vetešník L., Halačka K., Nowak M., Čížková D.: Permanent Genetic Resources added to Molecular Ecology Resources Database 1 April 2012 – 31 May 2012, Molecular Ecology Resources 12 (2012) 972-974.

Sivka U., Halačka K., Sušnik Bajec S.: Morphological differences in the skin of marble trout Salmo marmoratus and of brown trout Salmo trutta, Folia Histochemica Et Cytobiologica 50 (2012) 255-262.


Prchalová M., Horký P., Slavík O., Vetešník L., Halačka K.: Fish occurrence in the fishpass on the lowland section of the River Elbe, Czech Republic, with respect to water temperature, water flow and fish size, Folia zoologica 60 (2011) 104-114.


Halačka K., Vetešník L., Mendel J., Papoušek I.: Can spawning marks on females of the spined loach (Cobitis sp., Teleostei) be caused by scratches from males during mating?, Folia zoologica 59 (2010) 329-331.

Halačka K., Vetešník L., Papoušek I., Mendel J., Šimková A.: The epidermal structure of Carassius gibelio: a link with ploidy status in spawning and postspawning periods, Journal of Fish Biology 77 (2010) 2171-2179.

Lusková V., Lusk S., Halačka K., Vetešník L.: Carassius auratus gibelio—the most successful invasive fish in waters of the Czech Republic, Russian Journal of Biological Invasions 1 (2010) 176-180.


Vetešník L., Halačka K., Papoušek I., Mendel J., Šimková A.: The first record of a natural hybrid of the roach Rutilus rutilus and nase Chondrostoma nasus in the Danube River Basin, Czech Republic: morphological, karyological and molecular characteristics, Journal of Fish Biology 74 (2009) 1669-1676.


Bartoňová E., Papoušek I., Lusková V., Koščo J., Lusk S., Halačka K., Švátora M., Vetešník L.: Genetic diversity and taxonomy of Sabanejewia balcanica (Osteichthyes: Cobitidae) in the waters of the Czech Republic and Slovakia, Folia zoologica 57 (2008) 60-70.

Flajšhans M., Rodina M., Halačka K., Vetešník L., Gela D., Lusková V., Lusk S.: Characteristics of sperm of polyploid Prussian carp Carassius gibelio, Journal of Fish Biology 73 (2008) 323-328.

Flajšhans M., Rodina M., Halačka K., Vetešník L., Gela D., Lusková V., Lusk S.: Charakteristika spermatu polyploidního karase stříbřitého, Carassius gibelio, Bulletin VÚRH Vodňany 44 (2008) 78-81.

Mendel J., Lusk S., Koščo J., Vetešník L., Halačka K., Papoušek I.: Genetic diversity of Misgurnus fossilis populations from the Czech Republic and Slovakia, Folia zoologica 57 (2008) 90-99.

Mendel J., Lusk S., Vasil'eva E. D., Vasil'ev V. P., Lusková V., Ekmekci F. G., Erk'kan F., Ruchin A., Koščo J., Vetešník L., Halačka K., Šanda R., Pashkov A. N., Reshetnikov S. I.: Molecular phylogeny of the genus Gobio Cuvier, 1816 (Teleostei: Cyprinidae) and its contribution to taxonomy, Molecular Phylogenetics and Evolution 47 (2008) 1061-1075.

Papoušek I., Lusková V., Koščo J., Lusk S., Halačka K., Povž M., Šumer S.: Genetic diversity of Cobitis spp. (Cypriniformes: Cobitidae) from different drainage areas, Folia zoologica 57 (2008) 83-89.

Papoušek I., Vetešník L., Halačka K., Lusková V., Humpl M., Mendel J.: Identification of natural hybrids of gibel carp Carassius auratus gibelio (Bloch) and crucian carp Carassius carassius (L.) from lower Dyje River floodplain (Czech Republic), Journal of Fish Biology 72 (2008) 1230-1235.