rss_2.0Sciendo RSS Feed for Croatian Journal of Fisherieshttps://sciendo.com/journal/CJFhttps://www.sciendo.comhttps://sciendo-parsed.s3.eu-central-1.amazonaws.com/66e338307d402026d60a265d/cover-image.jpghttps://sciendo.com/journal/CJF140216https://sciendo.com/article/10.2478/cjf-2024-0015<abstract> <title style='display:none'>Abstract</title> <p>The diet composition of painted comber <italic>Serranus scriba</italic> was studied in the eastern central Adriatic Sea. The stomach contents of 275 individuals with a total length (TL) between 10.8 and 24.1 cm, collected by a small beach seine from January to December 2017, were analyzed. The food items in stomachs belonged to seven prey groups: Gastropoda, Bivalvia, Polychaeta, Decapoda, Isopoda, Stomatopoda and Teleostei. Overall, decapods were the most important prey group (%IRI = 54.0), followed by teleosts (%IRI = 40.4%). All other prey groups had much lower %IRI values and thus were of less importance. Painted comber had a diverse diet, feeding on a higher number of prey items (<italic>H’</italic> = 3.11), and can be considered an opportunistic feeder whose diet in the Adriatic Sea consists of different groups of benthic organisms, with a wide range of prey sizes and morphology. For fish of small and medium size (up to 20 cm TL), decapods were the most important prey, whereas large-sized individuals (&gt; 20 cm TL) mainly consumed teleosts. Decapods were the most important prey in spring, summer and autumn, whereas teleosts dominated in winter.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00152024-09-12T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0012<abstract> <title style='display:none'>Abstract</title> <p>Tank goby <italic>Glossogobius giuris</italic> is widely distributed across Vietnamese rivers, estuaries, and lagoons, particularly in the central region where this species plays a pivotal role as a high commercial source for local communities. In this study, we employed landmark-based geometric morphometrics to compare the morphometric variations among three distinct populations of <italic>G. giuris</italic> inhabiting the Tam Giang Lagoon (Thua Thien Hue Province), Nhat Le Estuary (Quang Binh Province), and Truong Giang River (Quang Nam Province), Vietnam. The analysis, utilizing Permutational Multivariate Analysis of Variance (PERMANOVA) with Mahalanobis distances, revealed significant differences in the body shape among the three populations (<italic>P</italic> &lt; 0.001). Specifically, with respect to the lateral side, the highest Mahalanobis distance was observed between specimens from the Tam Giang and Nhat Le, followed by the Tam Giang and Truong Giang River, with the lowest value found between the Nhat Le and Truong Giang. A similar pattern was observed for the dorsal side. Canonical variate analysis (CVA) illustrated three distinct groups with statistical significance in all cases (<italic>P</italic> &lt; 0.001) and the confusion matrix showed a high corrected grouping rate of 88.5% for the lateral side and 82.8% for the dorsal side. These findings indicated notable variations in the body shape of <italic>G. giuris</italic> among the three studied areas. Fish sampled from the Tam Giang Lagoon exhibited a streamlined body shape, while those from the Truong Giang River and Nhat Le Estuary displayed a deeper body profile. The observed morphological differences among these fish populations are likely attributed to phenotypic adaptations driven by environmental factors and habitat distinctions. Importantly, this study marks the first attempt to compare the body shape variations of <italic>G. giuris</italic> in both freshwater and estuarine environments within central Vietnam, utilizing a landmark-based geometric approach. These findings provide crucial insights for further investigations into the ecological adaptations and evolutionary processes of this fish species.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00122024-09-12T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0014<abstract> <title style='display:none'>Abstract</title> <p>The aim of our study was to investigate the genetic variability of two members of two evolutionary different classes of the Acanthocephala, Eoacanthocephala (<italic>Neoechinirhynchus</italic> sp.) and Palaeacanthocephala (<italic>Acanthocephalus</italic> sp.) from the same host, <italic>Squalius cephalus</italic>, from rivers of the Adriatic (rivers in Lika region: Lika, Novčica, Bogdanica and Jadova) and the Black Sea basins (Medsave location on the Sava River) in Croatia. The samples were collected from May 2021 to July 2022. To put the genetic position of the analyzed acanthocephalans in a broader context, the COI sequences of other specimens from the NCBI GenBank were used. BLAST analysis of partial COI sequences of acanthocephalans showed the presence of two different species: <italic>Acanthocephalus</italic> sp. and <italic>Neoechinorhynchus</italic> sp. <italic>Acanthocephalus</italic> sp. specimens did not show different grouping related to geographical origin (Bogdanica, Lika, Jadova) or Black Sea basin (Medsave-Sava River). <italic>Acanthocephalus</italic> cluster was subdivided into five main subclusters and 13 haplotypes were determined. When we compared our haplotypes with those from the NCBI GenBank, our haplotypes were closer to the <italic>A. anguillae</italic> specimens from the Kupa River and Dobra River in Croatia, and also to the haplotypes from Austria. For the species <italic>Neoechinorhynchus</italic> sp. from the Lika River and the specimens from the NCBI GenBank, four haplotypes were found out of five specimens. This genus was recorded for the first time in the Lika River area and for the first time in European chub in Croatia. The closest species <italic>Neoechinorhynchus</italic> sp. from Austria and Finland were grouped separately. Due to the lack of NCBI GenBank data for this species from other geographical regions, our data could not be compared. This shows that the taxonomy of the genus <italic>Neoechinorhynchus</italic> from Europe remains a challenge and underlines the need for further DNA sequence data and in-depth morphological study.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00142024-09-12T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0011<abstract> <title style='display:none'>Abstract</title> <p>The sympathoadrenal system plays an essential role in forming the body’s response to the action of stimuli of various natures and intensities. The content of deposited catecholamines in peripheral blood erythrocytes is one of the most accessible parameters for an adequate description of the functional activity of the sympathoadrenal system in humans and rats. The aim of the work is to assess the accumulation of catecholamines in erythrocytes of sea ruffs <italic>Scorpaena porcus</italic> L. at various pollution levels in the bays of Sevastopol. The phenomenon of accumulation of catecholamines in erythrocytes of the peripheral blood of fish is revealed. The concentration of erythrocytes with deposited catecholamines was higher in fish from polluted bays. In 2006, fish from Alexander Bay exhibited a significantly higher erythrocyte content of deposited catecholamines (36.04%) compared to those from the background area (28.19%) and Quarantine Bay (30.74%) (<italic>P</italic> &lt; 0.01). Similar levels were observed between Quarantine Bay and the coast of Balaklava. In 2007, fish from Alexander Bay maintained a high erythrocyte catecholamine content (35.2%), while those from Quarantine Bay exhibited a lower level (23.8%) (<italic>P</italic> ≤ 0.01). In 2008, the erythrocyte catecholamine content in Quarantine Bay was six times higher than that observed in fish from Martynov Bay. These findings underscore the variability in catecholamine concentrations among fish populations inhabiting different coastal regions, suggesting potential environmental influences on stress responses..</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00112024-09-12T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0013<abstract> <title style='display:none'>Abstract</title> <p>The present study focuses on the detailed description of postovulatory follicles (POFs) resorption and atresia in horse mackerel from Algerian waters. From February 2013 to February 2014, 155 female horse mackerel were randomly collected. Histological sections of ovaries were analyzed. Few POFs (7.28% of early POFs and 2.91% of old POFs of the total observed oocytes) were detected. Morphological changes of POF resorption were discussed in the current study. No particular shape was observed. Four types of atretic oocytes were determined: α = 34.38%, β = 5.28%, δ = 2.37% and γ = 0.94%, which was reported for the first time in horse mackerel. The incidence of α atresia was higher in the yolked (21.48%) than in the unyolked oocytes (12.89%). α atretic oocytes can be classified into two main types: non-bursting (capsulated, lipoidal and cystic atresia) and bursting (multiple bursts, single bursts, phagocytic bursts and liquified bursts). Further studies are required to better understand the reproductive strategies of fish in relation to postovulatory follicle resorption and atresia.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00132024-09-12T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0008<abstract> <title style='display:none'>Abstract</title> <p><italic>Litopenaeus vannamei</italic>, a highly adaptable shrimp species known for its growth, thrives in environmental conditions with proper water quality. However, salinity stress poses a significant challenge, compromising shrimp survival and growth. To optimize shrimp feed, the inclusion of alginate and <italic>Spirulina</italic> sp. offers benefits such as enhanced growth and resistance to environmental stress. This research aims to assess the impact of adding <italic>Spirulina</italic> sp., alginate, and their combination on the survival rate, resistance to the salinity shock test, and growth of <italic>L. vannamei</italic>. In this study, a completely randomized design (CRD) method with nine different feed doses was used. The treatments included control, supplementation of Alg 1 (alginate 1 g/kg feed), Alg 3 (alginate 3 g/kg feed), Alg 5 (alginate 5 g/kg feed), Sp 3 (spirulina 3 mg/kg feed), Sp 6 (spirulina 6 mg/kg feed), Sp 9 (spirulina 9 mg/kg feed), AS 1+1 (alginate 1 g/kg feed + spirulina 1 mg/kg feed), AS 2+3 (alginate 2 g/kg feed + spirulina 3 mg/kg feed), and AS 3+5 (alginate 3 g/kg feed + spirulina 5 mg/kg feed). The supplementation of feed was given during the fourteen-day rearing period. The results of the study show that the supplementation of Sp 9 (spirulina 9 mg/kg feed) led to a significant growth (<italic>α</italic> = 0.05). All treatments supplemented with alginate and/or <italic>Spirulina</italic> sp. water extract had a significant effect (<italic>α</italic> = 0.05) on the resistance to the salinity shock test. The different treatments in <italic>L. vannamei</italic> feed supplementation significantly influenced (<italic>α</italic> = 0.05) shrimp survival. Polysaccharides and antioxidant properties in alginate and <italic>Spirulina</italic> sp. have an important role in increasing the growth and resistance to salinity shock of <italic>L. vannamei</italic>.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00082024-05-30T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0007<abstract> <title style='display:none'>Abstract</title> <p>A study was conducted on the changes in sea surface temperature (SST) on the southwestern shelf of the Crimea between 2000 and 2020. The equations of trends in the change of SST were found. It is shown that the following three periods can be distinguished according to the nature of changes in the average annual sea temperature: 2000 - 2007, 2008-2013 and 2014 - 2020. The influence of changes in the average annual SST on the development of pelagic fish of the cold-water complex was considered (using the example of the Black Sea sprat). Changes in the main parameters of the populations and their relationship with the change in the average annual SST were determined. It was found that the increase in sea temperature negatively affected the development of the sprat population, and the average age of the population decreased by 1.3 times. In general, the population was rejuvenated, and the average size and weight of individuals decreased.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00072024-05-30T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0010<abstract> <title style='display:none'>Abstract</title> <p>Huchen or Danube salmon <italic>Hucho hucho</italic> (Linnaeus 1758) is one of the largest salmonid species in the world and the largest species native to the Danube basin in Europe. In Serbia, this species inhabits the Drina river system, as well as the upper reaches of the River Ibar. It has already been introduced into the rivers Moravica and Đetinja, which are part of the Zapadna Morava catchment area. Most recently, huchen was stocked from its native habitat into the rivers Jerma and Nišava in the Južna Morava river system, and into the River Mlava which flows into the Danube. Huchen is listed as an endangered (EN) species on the IUCN Red List of Threatened Species and is protected in Serbia, and a Conservation Action Plan has already been adopted. In this report, we present the first record of this species in the River Grza, which is a part of the Velika Morava river system, outside its native range. The ichthyofauna of this recipient river consists of brown trout <italic>Salmo trutta</italic> L. and Eurasian minnow <italic>Phoxinus phoxinus</italic> L. In a small river of a fragile ecosystem such as this, the introduction of huchen as an apex predator can seriously harm the species of the native fish community, which warns of the illegal stocking measures currently in process.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00102024-05-30T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0009<abstract> <title style='display:none'>Abstract</title> <p>Carotenoids are naturally occurring pigments in plants, algae, fungi, insects, and crustaceans. Krill and prawns contain high levels of some value-added nutrients for the aquaculture industry, such as astaxanthin which is used as a colouring agent. In birds with ornamental plumage, such as canaries, the carotenoid-pigmented plumage and red hues are exclusively due to the diet. In this regard, our aim was to study the possibilities of using shrimp waste for feather colouring in canary <italic>Serinus canaria domestica</italic>. Shrimp <italic>Pandalus borealis</italic> dried waste was included in the feed of six female red lipochrome mosaic canaries <italic>Serinus canaria domestica</italic> for three months during their third molt. The basic diet consisted of a seed mixture (canary seed, sunflower seed without shell, linseed, and rapeseed), rearing food (Quiko®Bianco), and conditioning food (Quiko®Rusk) with the supplementation of an oil suspension of dried shrimp waste (3%). The <italic>ad libitum</italic>-fed birds had additional free access to pasta (Legazin® Procria White Morbida). To evaluate the effect of shrimp waste on feather colouring, covert feathers were taken from the tail in the region of the uropygial gland. Diffuse reflectance spectroscopy of the most intensely coloured parts of the feathers was measured by a spectrophotometer. The chromaticity coordinates in a CIE xyY colour space were calculated from the measured spectroscopy. The results of the experiment showed that shrimp waste increased chromaticity and had no negative effect on the canaries. On this basis, the authors assumed that dried shrimp waste could be an alternative to synthetic dyes.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00092024-05-30T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0006<abstract> <title style='display:none'>Abstract</title> <p>Nile tilapia <italic>Oreochromis niloticus</italic> is one of the most important fishery resources and a valuable fish species for aquaculture programmes. It is found in almost all waters and is widely dispersed. Several natural populations of this species have been impacted by genetic pollution despite their significant economic relevance. Understanding population structure is a crucial first step in protecting this species in its native habitats as well as in choosing which wild stocks to use in hatchery initiatives. To demonstrate the genetic-population structure of this species, genetic differences among three geographically secluded populations of <italic>O. niloticus</italic> were investigated utilizing mitochondrial DNA cytochrome b gene sequences. The results were used to estimate the levels of genetic variability within and among the populations. The 56 cyt b (821 bp) sequences analysis revealed 21 haplotypes, with a nucleotide diversity of 0.0510 and a haplotype diversity of 0.881. In each of the populations, seven (7) singleton variable sites and 19 informative-parsimony sites, genetic diversity could be identified and few population haplotypes were found, indicating a minor genetic distinction between them. For the purpose of conservation and/or Nile tilapia breeding programmes, this information would assist in choosing the fish populations that maintain greater genetic variation in <italic>O. niloticus</italic>.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00062024-05-30T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0002<abstract> <title style='display:none'>Abstract</title> <p>Devil firefish <italic>Pterois miles</italic> is an invasive alien species which has severely impacted biodiversity and ecological processes in invaded areas of the Mediterranean. In recent years, its presence has been documented in several countries of the Adriatic Sea. Based on the negative ecological and socio-economic impacts in other areas of the Mediterranean Sea, the potential invasiveness of devil firefish was analyzed for the coastal areas of the three eastern Adriatic countries (Albania, Croatia and Montenegro) using the <italic>Aquatic Species Invasiveness Screening Kit</italic>. Generally, based on the average value of the Basic Risk Assessment and the threshold used, the outcomes suggest that this species will be highly invasive in the eastern Adriatic countries. In addition, the results have shown that the most affected sector is represented by the local species populations and relative characteristics, while commercial sectors represent the least affected sector. However, considering that the negative impact of non-native species is not seen directly, the governments of these countries should address this issue as soon as possible.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00022024-03-08T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0001<abstract> <title style='display:none'>Abstract</title> <p>This study examined the effects of dietary supplementation of queen scallop <italic>Aequipecten opercularis</italic> with an indigenous strain of lactic acid bacteria (LAB), <italic>Lactiplantibacillus plantarum</italic> I, previously isolated from its digestive tract, on gut microbial populations and growth rates during cultivation under simulated climate change conditions (pH 7.8, T = 16 ± 2 °C). After one month of feeding, the results showed a noticeable reduction in aquaculture diseases causing pathogens while maintaining sufficient viable <italic>Lpb. plantarum</italic> I cells. A higher pH and temperature resulted in higher growth rates, measured by the weight and length of scallops, compared to the control group. The results obtained shed light on the influence of the addition of lactic acid bacteria on the growth of bivalve mollusks under normal and climate change conditions, and provide control of pathogenic microorganisms. In the context of climate change, host-pathogen interactions need to be recognized and put under control by applying natural solutions to minimize the environmental footprint.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00012024-03-08T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0004<abstract> <title style='display:none'>Abstract</title> <p><italic>Chlamydomonas</italic> spp. and <italic>Chlorella</italic> spp. are plankton genera that can be used to determine the level of balance in the aquatic environment. The purpose of this study is to determine the abundance of plankton <italic>Chlamydomonas</italic> spp. and <italic>Chlorella</italic> spp. and its relation to the clinical performance of red tilapia in silvofishery ponds. The research method used is an <italic>ex post facto</italic> causal design with random sampling. The results showed that the water quality in the silvofishery ponds was very good, except for the nitrate parameters of 0.00-1.50 mg/L and salinity of 2-11 gr/L, which exceeded the quality standards. In the silvofishery ponds, 5 plankton classes were found, namely Chlorophyceae, Cyanophyceae, Chrysophyceae, Protozoa, and Dinophysis, consisting of 15 genera. The dominant class Chlorophyceae had an abundance of 2.88E+06 cells/ml. The class Chlorophyceae is dominated by <italic>Chlorella</italic> spp. (2.63E+06 cells/ml) and <italic>Chlamydomonas</italic> spp. (2.20E+05 cells/ml). The abundance of <italic>Chlamydomonas</italic> spp. in silvofishery ponds is closely related to phosphate solubility (0.988). Based on observations of clinical symptoms on the eyes, gills, and fins of fish, no disease infections or physical abnormalities were found in the fish cultured in silvofishery ponds. Fish tend to live well with a growth rate of 0.44 g/day. The aquatic ecosystem of the silvofishery pond, which is dominated by the plankton <italic>Chlorella</italic> spp. and <italic>Chlamydomonas</italic> spp., had a good effect on the performance and condition of the farmed fish. This study concludes that the abundance of <italic>Chlamydomonas</italic> spp. and <italic>Chlorella</italic> spp. was very dominant compared to other plankton genera. The presence of <italic>Chlamydomonas</italic> spp. and <italic>Chlorella</italic> spp. illustrates good and stable environmental conditions in silvofishery ponds, followed by no clinical signs of disease infection in the fish reared during the study period.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00042024-03-08T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0005<abstract> <title style='display:none'>Abstract</title> <p>The aim of this study is to analyse the development of artisanal fish catch by species in the Croatian section of the Sava River. For Abramis brama and <italic>Silurus glanis</italic>, a significant decline in catches (in kg) was observed throughout the study period (2004-2021). Since 2013, this has also been the case for <italic>Cyprinus carpio, Esox lucius, Sander lucioperca,</italic> other autochthonous species and alochthonous species, while catches of <italic>Leuciscus idus</italic> have declined significantly since 2014. The catches of three species (<italic>Acipenser ruthenus, Leuciscus aspius</italic> and <italic>Tinca tinca</italic>) fluctuated without a trend, which can be attributed to the low quantities. This decline in catches of the most sought-after species in the Sava was greater than that of the other less sought-after autochthonous species (mainly other cyprinids), whose share of the total catch increased significantly.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00052024-03-08T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2024-0003<abstract> <title style='display:none'>Abstract</title> <p><italic>Magallana bilineata</italic> is a commercially important oyster species in Malaysia. Despite its economic significance, the biology and ecology of this species, particularly its reproductive cycle, are poorly understood in the region. Therefore, this study aimed to investigate the reproductive cycle of <italic>M. bilineata</italic> in Mengkabong Bay, Tuaran, Sabah and its correlation with environmental factors. A total of 105 oyster specimens were collected and examined to determine the sex ratio, gonad developmental stages, maturity index (MI), and condition index (CI). The results revealed a sex ratio of 1:2.36 (♂:♀) in the oyster population of the bay, with a significantly higher proportion of females (<italic>P</italic> &lt; 0.05). Hermaphroditism was detected in 1.90% of the samples. <italic>M. bilineata</italic> was found to spawn throughout most months in the bay, with the highest MI and CI values recorded in November 2019 when most oysters were in mature or maturing stages. Salinity was found to be the primary factor influencing male gonad maturation, while temperature was the primary factor influencing female gonad maturation. Understanding the reproductive biology of this species is crucial for predicting its future survival and facilitating assisted spawning and hatchery spat production, thereby ensuring the conservation and sustainability of the oyster fishery in Malaysia.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2024-00032024-03-08T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2023-0018<abstract><title style='display:none'>Abstract</title> <p>Round goby <italic>Neogobius melanostomus</italic> is one of the three invasive Ponto-Caspian gobies found in the Sava River basin in Croatia. It has a negative effect on the native ecosystems and is more abundant in highly polluted areas. The objective of this study was to determine the fluctuating asymmetry of four morphometric characters, as well as otolith width and length. Thirty individuals of <italic>N. melanostomus</italic> were collected and analysed at two sampling sites in the main course of the Sava (Babina Greda, Slavonski Brod) and in a modified habitat (Sava-Odra canal). The squared coefficient of asymmetry variation was used to analyse potential differences between populations. We identified variations in the asymmetry values of the analysed characters, as well as otolith width and length between sampling sites. The highest fluctuating asymmetry was observed in individuals at the Babina Greda sampling site, which could be due to high environmental stress. The results of the study show that the study of fluctuating asymmetry can be used on invasive fish species as a simple approach to identifying habitat quality.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2023-00182023-11-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2023-0019<abstract><title style='display:none'>Abstract</title> <p>Goonch <italic>Bagarius bagarius</italic> (Hamilton, 1822) is one of the largest and fastest-growing catfish of the Indus River found at Taunsa Barrage, Pakistan. The full-length cDNA of the growth hormone gene (600 bp) was amplified by reverse transcription of mRNA isolated from the pituitary gland of <italic>B. bagarius</italic>. The full-length growth hormone gene encodes a putative polypeptide of 200 amino acids with a molecular mass of 22.58 kDa. The precursor of <italic>B. bagarius</italic> growth hormone (GH) is composed of 22 amino acids as a signal peptide and 178 amino acids of a mature peptide. There were six conserved Cys residues in GH protein (20, 71, 135, 173, 190 and 198) that maintain the structural integrity of this protein. One putative N-glycosylation site was present at the 197^th amino acid. The total number of positively charged (Arg and Lys) and negatively charged (Asp and Glu) residues is 42 and 31, respectively. The <italic>B. bagarius</italic> GH gene shows more than 90% sequence homology with other catfishes. The mature protein GH gene was expressed in <italic>Escherichia coli</italic> using pET-28 expression vector, and the recombinant protein of 19.5 kDa was detected through SDS-PAGE analysis. This study suggests that cloning and expression of <italic>B. bagarius</italic> GH gene would provide basic information for transgenic studies aimed at a faster growth rate. This recombinant GH may be produced on a large scale to exploit its growth-promoting function in other cultured fishes.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2023-00192023-11-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2023-0017<abstract><title style='display:none'>Abstract</title> <p>As an endemic species, Dalmatian barbelgudgeon was introduced into Šatorsko Lake, but it was insufficiently explored at this locality. The aim of this study was to determine seasonal variations of physicochemical parameters of the water in relation to morphometric and hematological parameters of Dalmatian barbelgudgeon from Šatorsko Lake. Physicochemical analysis of the water recorded lower values of temperature, O₂ concentration, O₂ saturation, electrolytic conductivity and suspended matter in autumn, while other analyzed parameters indicated lower values in spring. The analysis of morphometric parameters (weight, standard length, total length and Fulton’s condition factor) determined higher values of all the parameters during spring, while a significant difference was noted only for Fulton’s condition factor. A statistically significant difference was observed for all erythrocyte lineage parameters (RBC-red blood cells, HB-hemoglobin concentration, HCT-hematocrit, MCV-mean corpuscular volume, MCH-mean corpuscular hemoglobin, MCHC-mean corpuscular hemoglobin concentrations). In white blood cells, a statistically significant difference was recorded for lymphocytes, non-segmented neutrophils and monocytes, while the proportion of segmented neutrophils and basophils was slightly increased in spring. Furthermore, the recorded values of pseudo-eosinophils were equal in spring and autumn. The results of these studies indicate a significant influence of exogenous and endogenous factors on the variability of morphometric and hematological parameters of Dalmatian barbelgudgeon from Šatorsko Lake. </p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2023-00172023-11-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2023-0016<abstract><title style='display:none'>Abstract</title> <p>This study is the first contribution to monitoring the rearing of common meagre <italic>Argyrosomus regius</italic> in floating cages anchored in Dakhla Bay, southern Morocco. The aquaculture potential of common meagre in Dakhla Bay was evaluated by zootechnical monitoring of two production cycles. The first batch consisted of 20,000 fingerlings of 4.5 ± 0.13 g in mean initial weight and 6±0.19 cm in fork length, and was caught on 26 August 2019 under a condition factor of about 2.08 ± 0.35. The second batch consisted of 30,000 individuals of 3 ± 0.11 g in average initial weight and 6±0.26 cm in average initial length, and was caught on 4 June 2020 under a condition factor of about 1.39 ± 0.21. During the first experiment, which lasted 16 months, a high growth potential of common meagre was observed. The fish reached an average weight of 1265 ± 69.2 g and an average length of 48±4.32 cm with a specific growth rate (SGR) of 0.58 ± 0.11% day^-1 and a daily growth index DGI of 2.45 ± 0.91 g ind^-1 day^-1. The feed conversion ratio was 1.18 (FER = 0.84), final density was 36.94 kg m^-3 and condition factor (k) recorded a mean value of 2.18±0.39 throughout the cycle. The survival rate at the first harvest was 89.86%. After 18 months of rearing, the fish of the second cycle reached a weight of 1285±69.2 g and a size of 47 ± 5.36 cm, with an SGR of 0.49 ± 0.12 % day^-1 and a DGI of 2.34 ± 1.35 g ind^-1 day^-1, an FCR of 1.21 (FER =0.83), the final density of 28.43 kg m^-3 and a condition factor of 1.35 ± 0.32. The survival rate was 92.19%. However, the results of the statistical analysis showed that there was no significant difference between the two production cycles (<italic>P</italic> &gt; 0.05). These results confirm that common meagre is a very promising species for the diversification of aquaculture in Dakhla Bay and throughout Morocco.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2023-00162023-11-14T00:00:00.000+00:00https://sciendo.com/article/10.2478/cjf-2023-0020<abstract><title style='display:none'>Abstract</title> <p>A specimen of common thresher shark <italic>Alopias vulpinus</italic> (Bonnaterre 1788) was caught in a fishing net in the waters off Piran (Gulf of Trieste, northern Adriatic Sea). It was a juvenile male with a total length of 2841 mm. In recent decades, other cases of juvenile specimens of common thresher shark have been recorded in Slovenian coastal waters. Despite the drastic decline in the population of this species, thresher shark continues to be caught in local Adriatic fisheries.</p> </abstract>ARTICLEtruehttps://sciendo.com/article/10.2478/cjf-2023-00202023-11-14T00:00:00.000+00:00en-us-1