Studying sanitary and hygienic conditions of bream and water in its habitat

The article highlights the data on microbiological monitoring of fish raw materials and water of the Volga-Caspian fishing channel in 2020-2021. The most indicative organisms for assessing the quality of the aquatic environment are benthos-eating fish. Bream Abramis brama (Linnaeus, 1758) is one of the valuable objects of fishing in the Astrakhan region. As a commercial object of river coastal fishing, bream has a higher bacterial contamination than fish caught in the sea. In this regard, studying the conditions for bacteriocenosis of fish raw materials, as well as the factors that determine the pathogenicity of its microflora and sanitary and epizootic monitoring by the microbiological tests remain the most relevant research of aquatic organisms. Quantitative and qualitative indicators of the bream microflora were estimated, according to the analysis of 180 species. The indicators of the water microflora were analyzed using the results of studies of 90 samples. The species identification of the isolated microflora was carried out according to the Bergey identification keys. In the samples of bream muscles there was determined the total number of facultative anaerobic microorganisms and aerobic mesophylls, presence of coliform microorganisms, as well as a causative agent of Staphylococcus aureus, pathogenic bacteria Salmonella and Listeria, and parahemolytic vibrios Vibrio. The study results were processed, according to the methods of biological statistics in the Microsoft Excel 2010 software. The results are presented as mean values and standard errors (M ± m). The general microbiological analysis of the fish muscle tissue confirmed the satisfactory sanitary state of bream Abramis brama (L., 1758) caught in the fishing area of the Volga-Caspian Canal during the study period. Pathogenic microflora in the form of E. coli bacteria, bacteria Salmonella, L. monocytogenes and St. aureus were not found

Fish helminths in reservoirs of the Zarafshan river

The results of the study of the helminth fauna of 8 species fish of the lower reaches reservoirs of the Zarafshan River are presented - carp (Cyprinus carpio), crucian carp (Carassius auratus gibelio), roach (Rutilus rutilus), oriental bream (Abramis brama), pike perch (Stizostedion lucioperca), silver carp (Hypophthalmichthys molitrix), pike (Esox lucius), Turkestan barbel (Barbus capito conocephalus). 27 species of helminths were identified, including 12 species of cestodes (Caryophyllaeus laticeps Pallas, 1781; Caryophyllaeus fimbriceps Annenkova - Chlopina, 1919; Biacetabulum appendiculatum Szidat, 1937; Khawia sinensis Hsu, 1935; Bathybothrium rectangulum Bloch, 1782; Bothriocephalus opsariichthydis Yamaguti, 1934; Ligula intestinalis Linnaeus, 1758 larvae; Digramma interupta Rudolphi, 1810 larvae; Proteocephalus torulosus Batsch, 1786; Neogryporhynchus cheilanoristrotus Wedl, 1855 larvae; Gryporhynchus pusillus von Nordman, 1832 larvae; Valipora campylancristrota Rudolphi, 1819 larvae), 5 species of trematodes (Sanguinicola inermis Plehn, 1905; Orientocreadium siluri Bychowsky et Dubinina, 1954; Allocreadium isoporum Looss, 1894; Diplostomum spathaceum Rudolvae, 1832 lare; (Dioctophyme renale Goeze, 1782 larvae; Rhabdochona denudata Dujardin, 1845; Desmidocercella numidica Seurat, 1920 larvae; Camallanus truncatus Rudolphi, 1814; Camallanus lacustris Zoega, 1776; Philometra ovatachenko Zeder, 1803; 1779 larvae) and 2 species of acanthocephalus (Pomphorhynchus laevis Muller, 1776; Acantocephalus lucii Muller, 1776). This work includes the results of the research of the helminthes of the fish of waterbodies in the lowers of the Zarafshan River. As a result, the infection of fish with 27 species of helminthes, belonging to cestodes (12), trematodes (5), nematodes (8), and acanthocephalans (2) was established.

Gill Histopathology as a Biomarker for Discriminating Seasonal Variations in Water Quality

Histopathological alterations in various fish organs have a pronounced value in aquatic toxicology and are widely used in environmental monitoring. The aim of this study was to evaluate whether histopathological alterations in fish gills can discriminate seasonal variations in environmental conditions within the same aquatic ecosystem, and if so, which alterations contributed the most to seasonal differentiation. Microscopic examination of common bream Abramis brama gills displayed various alterations in gill structure, including epithelial hypertrophy, hyperplasia, mucous and chloride cell alterations, epithelial lifting, necrosis, hyperemia and aneurism. These alterations were subsequently quantified by a semi-quantitative analysis in order to detect differences in the intensity of the mentioned alterations. Epithelial hypertrophy, hyperplasia, epithelial lifting and necrosis varied significantly between seasons with only necrosis being significantly higher in the first season. Discriminant canonical analysis displayed that epithelial hyperplasia, mucous cell alterations, epithelial lifting and necrosis contributed the most to discrimination between seasons. Overall, this study demonstrates that histopathological biomarkers in fish gills can be used in discriminating seasonal variations in water quality within the same aquatic ecosystem.

Evaluation of the Composition of Ichthyofauna in Lakes Free from Commercial Use in a Tightly Protected Area of the Wolin National Park (Poland)

The ichthyological biodiversity of Polish lakes is poorly understood, even in lakes not used for fishing and those under strict protection. With this in mind, the aim of this study was to conduct a comprehensive ichthyological survey of several lakes in the Wolin National Park (Poland). The study was conducted in Domysławskie and Gardno lakes and the anthropogenic Stara Kredownia reservoir. Each fishing exercise was conducted using benthic nets over a 12 h period. The fish caught were measured and weighed, and the species identified. Shannon-Wiener (H) and Simpson biodiversity indices were determined. The catch comprised a total of 4580 fish (of which 4391 were caught in Domysławskie Lake) belonging to 15 species, with a combined weight of 98,165 g. In general, the most prevalent species were non-predatory fish: roach (Rutilus rutilus), freshwater bream (Abramis brama), white bream (Blicca bioerkna), bleak (Alburnus alburnus), and rudd (Scardinius erythrophthalmus). Individually, perch (Perca fluviatilis) and roach (Rutilus rutilus) were the most abundant species. Ichthyofauna diversity varied greatly between the studied water bodies, with 15 species found in Domysławskie Lake and only 6 species in Gardno Lake. In Stara Kredownia Reservoir, no fish were caught, but amphibians were observed, such as great crested newts (Triturus cristatus) and common newts (Lissotriton vulgaris). Based on the results obtained, Lake Domysławskie had a higher species ichthyofauna diversity than the other ‘tench and pike’ lakes. Gardno Lake had a much lower biodiversity.

Ichthyofauna of some reservoirs of local significance in Aksu district, Pavlodar region

In 2020, research works were carried out on seven reservoirs of local significance in Aksu district, Pavlodar region. These are Lake Komendant, Lake Krasnoe, Lake Lesnoe, Lake Topalevoe, Lake Kara Murza, Lake Baltazhar and the Karasu Channel. In these reservoirs, the ichthyological composition was studied, such fish species as pike (Esox lucius L., 1758), silver carp (C. gibelio (Bloch, 1782)), golden carp (Carassius carassius (L., 1758)), rotan (Perccottus glenii Dybowski), tench (Tinca tinca (L., 1758)), perch (Perca fluviatilis L. ,1758), roach (Rutilus rutilus (L., 1758)), carp (Cyprinus carpio L.,1758), and bream (Abramis brama (L., 1758)). The species of fish included in the Red Book of the Republic of Kazakhstan, as well as rare or endangered, are not marked in the research catches of the studied reservoirs.

SOME INFORMATION ON THE CARP FISH SPECIES FEEDING

The article presents the results of studies of feeding characteristics of such cyprinid fish species as the roach Rutilus rutilus caspius (Jakowlev, 1870) and the bream Abramis brama (Linnaeus, 1758) in various parts of the Daghestan coast of the Caspian Sea. The material was sampled along the entire Daghestan coast of the Caspian Sea, from the Kizlyar Bay to the mouth of the Samur river, in different biological seasons in the period of 2017–2018.