Croatian Journal of Fisheries Feed

The Relationship of Microplastic Abundance in Green Mussel Perna Viridis and the Waters of Mangkang Beach, Semarang

Tue, 17 Mar 2026 00:00:00 GMT

Plastic, especially microplastics, currently poses a potential threat to water pollution. Microplastics are found not only in water but also in aquatic biota. Green mussels Perna viridis cultivated in Mangkang Wetan coastal waters may be contaminated with microplastics. This research aimed to determine the abundance of microplastics by shape, colour, and polymer type, and to examine the relationship between the abundance of microplastics in the aquatic environment and green mussels P. viridis. Data collection was carried out using a random sampling method to assess the distribution of green mussel cultivation by collecting water samples and green mussels, which were analyzed using quantitative methods. Data analysis was performed using ANOVA and regression analysis. The research identified 4 types of microplastic forms in the waters and 3 in green mussels, with fragment forms dominant in both. Seven colours were found (yellow, green, blue, black, transparent, brown and red), with brown being the dominant colour. Nine types of polymers were identified (polyvinyl chloride, polyethylene terephthalate, polypropylene, low-density polyethylene, high-density polyethylene, nylon, cellulose acetate, polyethersulfone and polystyrene), with polyethylene terephthalate as the dominant polymer. The abundance of microplastics in the waters and green mussels at Station 1 was 6.33 ± 0.45 particles/liter and 4.91 ± 2.32 particles/ind, at Station 2 it was 2.33 ± 0.49 particles/liter and 1.33 ± 0.28 particles/ind, and at Station 3 it was 4.63 ± 0.32 particles/liter and 2.91 ± 1.18 particles/ind. The ANOVA results for microplastic abundance in the waters showed a significance value of 0.00 < 0.05. The ANOVA results for green mussel microplastic abundance showed a significance value of 0.072, which is > 0.05. The regression analysis showed an exponential pattern, with a coefficient of determination (R2) of 0.685.

Spatial Variability in Growth and Condition of Nile Tilapia Oreochromis Niloticus Linked to Pollution Gradients in the Nile River, Egypt

Tue, 17 Mar 2026 00:00:00 GMT

This study investigated spatial variations in growth, condition factor, age, and longevity of Oreochromis niloticus populations along a pollution gradient in the Nile River, Aswan, Egypt. We compared a reference site (Ferial, Site I) with two polluted sites: El-Sail Drain (Site II) and Kom Ombo (Site III). Water and fish samples were collected monthly from January to December 2021 to analyze physicochemical parameters, heavy metals, age structure, growth, and condition factor. The results revealed significant spatial disparities. Fish from Site I exhibited the highest growth potential, with an asymptotic length (L∞) of 27.22 cm, a growth coefficient (K) of 0.17 year−1, and a maximum age of 13.5 years. In contrast, populations from Site II and Site III showed reduced growth (L∞ = 25.46 and 24.52 cm, respectively), higher K values (0.19 and 0.24 year−1, respectively), and shorter lifespans (11.9 and 9.2 years, respectively). Although the growth performance index (Ø) was similar among sites, annual length increments and condition factors were significantly lower at the polluted sites. These findings demonstrate that environmental degradation, primarily from industrial and domestic wastewater, adversely affects the somatic growth and physiological conditions of O. niloticus, highlighting the urgent need for enhanced pollution control and management strategies in the Nile River.

Species-Specific Evidence of Structural Change in Portuguese Fisheries: A 30-Year Analysis of CFP Reform Influence

Tue, 17 Mar 2026 00:00:00 GMT

This study provides the first national, species disaggregated quantitative assessment of structural changes in Portuguese marine fisheries over three decades (1995 – 2024), coinciding with major reforms of the European Union’s Common Fisheries Policy (CFP). Using annual landings data for 47 species, Spearman rank correlation was applied to detect long term monotonic trends between year and landing volume, a non parametric approach robust to non normality, zeros, and outliers. Results reveal a pervasive decline: 26 species (55.3%) exhibited significant negative trends (ρ as low as −0.953, P < 0.001), including commercially important demersals such as European hake and gurnards. Conversely, 9 species (19.1%) showed significant positive trends (e.g. Atlantic mackerel, European sea bass; ρ up to +0.778, P < 0.001), while 12 species (25.5%) remained statistically non significant. These patterns are directionally consistent with CFP objectives to reduce fishing mortality and promote selective exploitation, while acknowledging alternative drivers such as climate variability and reporting changes. The findings indicate systemic restructuring of Portuguese fisheries, with widespread reductions in demersal landings and selective increases among pelagic species, reflecting adaptive responses to regulatory and ecological pressures. This work contributes novel species level evidence of long term structural transformation, offering a baseline for future causal analyses using interrupted time series or multivariate approaches. By quantifying monotonic trends across 47 species, the study enhances understanding of policy aligned shifts in fleet behavior and ecosystem exploitation, informing adaptive governance and sustainability strategies under evolving EU fisheries frameworks.

Sustainability Assessment of Coral Reef Ecosystem in Panjang Island, Jepara, Central Java

Tue, 17 Mar 2026 00:00:00 GMT

Panjang Island, Jepara, is a conservation area in the northern part of Jepara Regency, Central Java, where the local community’s economy relies on capture fisheries and tourism. However, human activities and environmental changes have degraded the coral reef ecosystem, threatening the island’s sustainability and local livelihoods. This study aimed to assess the sustainability status of Panjang Island across various dimensions in response to these significant pressures. A descriptive quantitative method was employed. Observations of ecological variables, such as coral cover and recruitment, were conducted using the line-intercept transect method, while reef fish were surveyed using underwater visual census methods, and biodiversity indices were calculated manually. The social, economic, and institutional dimensions were assessed through interviews and focus group discussions. Although the ecological, institutional, and social dimensions are moderately sustainable, the main finding indicates that the economic dimension remains less sustainable. Enhancing community participation, governance, and capacity-building programmes is essential to support sustainable resource use and protect the island’s ecosystem in the long term. These findings highlight the urgent need for synergistic and holistic management strategies that prioritize the improvement of local economic opportunities. Such an integrated approach is crucial for achieving balanced and genuinely sustainable coral reef management on Panjang Island.

Changes in the Proportion of Fish Species Caught by Artisanal Fishers in the Croatian Section of the Sava River

Tue, 17 Mar 2026 00:00:00 GMT

The number of artisanal fishers, and consequently their catch, in the Sava River has declined significantly over the past two decades. The average weight of some species has also changed significantly. Therefore, the aim of this paper is to investigate possible changes in the biomass proportion in the catch of the most important taxa during this period. Most of the investigated species showed considerable variation in catch from year to year, but without a clear trend (P > 0.05). The largest fluctuations, with a coefficient of variation (CV) over 90%, were found in Acipenser ruthenus, Cyprinus carpio, Leuciscus aspius and allochthonous species. Esox lucius, Leuciscus idus, Silurus glanis and Sander lucioperca had CVs between 41% and 73%. The smallest variations in the proportion of catch were recorded for Abramis brama and other autochthonous species (the most abundant being Rutilus virgo), with CVs of 37.77% and 33.43%, respectively. These two taxa also showed significant opposite trends (R² = 0.34; P < 0.01) and had a combined average biomass proportion of 67.03%.

The life and work of Metka Povž (1944–2024), a leading Slovenian ichthyologist

Wed, 31 Dec 2025 00:00:00 GMT

Dr. Metka Povž (1944–2024) was a distinguished Slovenian ichthyologist whose career spanned over five decades, during which she authored more than 500 publications, both scientific and professional. Her work significantly advanced knowledge of freshwater fish in Slovenia and the broader Balkan region, with particular emphasis on species inventories and fish conservation. This paper reviews her major scientific contributions, including her role in protecting endangered native fish species, such as the preservation of pure populations of marble trout Salmo marmoratus, her research on non-native fish species, and her involvement in the protection of freshwater habitats. Her work remains a cornerstone in the field of ichthyology in the region and continues to inspire the ichthyological community.

Acute toxicity impact of indoxacarb on gill neuroendocrine system and brain of stinging catfish Heteropneustes fossilis

Wed, 31 Dec 2025 00:00:00 GMT

The recent study aimed to evaluate the impact of acute toxicity of indoxacarb (IDC) on pseudobranchial neurosecretory cells (PNSCs), biochemical assays and histopathological changes in the brain, and accompanying behavioral abnormalities in the air-breathing stinging catfish Heteropneustes fossilis. The 96-hour LC50 of IDC was ascertained at a dose of 0.075 mg/L. Live catfishes were exposed to LC50 dose of IDC for 24, 48, 72 and 96 hrs, and the respective parameters were studied at predetermined intervals. After 96 hrs of exposure to IDC, histopathology of PNSCs demonstrates degenerative changes, reduced neurosecretory material, significantly decreased number of PNSCs along with nucleocytoplasmic (N/C) ratio, as compared to the control group. The exposed fishes displayed detachment of stratum marginale (SM) and stratum opticum (SO), mild necrosis in stratum periventricular (SPV), and compact neuroarchitecture of stratum fibrosum et grisium superficiale (SFGS), stratum griseum centrale (SGC) and stratum album centrale (SAC), whereas degeneration of mononuclear cells and Purkinje cells in the cerebellum was observed. The acetylcholinesterase (AChE), superoxide dismutase (SOD), and catalase (CAT) activities were significantly decreased, whereas malondialdehyde (MDA) level was significantly increased, as compared to the control group. The total distance traveled, swimming speed, mobility time, absolute turn angle, head: distance traveled, and maximum speed were significantly decreased, whereas immobility time, maximum inactive episode, and time freezing were significantly increased in comparison with the control group. This study concludes that acute toxic concentrations of IDC may cause physiological dysregulation, biochemical changes in brain tissues and mild necrotic changes in PNSCs and neuronal cells in fish, resulting in substantially associated behavioral disturbances.

The effect of the addition of papaya seed flour Carica papaya L. in feed on the immune response and growth performance of whiteleg shrimp Litopenaeus vannamei

Wed, 31 Dec 2025 00:00:00 GMT

The main issues in shrimp farming are disease and high feed prices. To overcome these issues, a safe and inexpensive substance that can improve health and growth is needed. Natural ingredients from plants such as papaya Carica papaya L. are widely available in Pekalongan. This study aimed to determine the effect of papaya seed flour as a substance addition to artificial feed on the immune response and growth performance of whiteleg shrimp. This experimental research employed a completely randomized design (CRD) consisting of five treatments and three replications. The test animals were whiteleg shrimp (PL21) post-larvae, while the test feed was supplemented with papaya seed flour at different doses for each treatment: 0 g.kg−1 feed (A); 1 g.kg−1 feed (B); 3 g.kg−1 feed (C); 5 g.kg−1 feed (D); and 7 g.kg−1 feed (E). The parameters observed included PA (Phagocytic Activity), THC (Total Haemocyte Count), absolute biomass, SGR (Specific Growth Rate), and FCR (Feed Conversion Ratio). Treatment D was identified as the optimal dose, resulting in PA of 65.67%, THC of 48.93 x 106 cells.mL−1, absolute biomass of 6.23 g, SGR of 6.09%.d−1, and FCR of 1.18, with a 100% survival rate. Data analysis confirmed that the treatments had a significant difference (P < 0.05) on all parameters. The results showed that the use of papaya seeds can improve both the health and growth of whiteleg shrimp.

Heavy metal concentrations in the muscle tissues and liver of three most commercial fish species from the River Vjosa – Aoos (Albania-Greece)

Wed, 31 Dec 2025 00:00:00 GMT

The concentrations of Fe, Mn, Zn, Cu, Pb and Cd in the muscle tissue and liver of chub Squalius platyceps, barbel Barbus prespensis and nase Chondrostoma vardarense were determined. These three species are among the most widely consumed by local people in the wide Vjosa Basin. Prior to this study, no research had been conducted on heavy metal bioaccumulation in the Vjosa River ecosystem. This research also intends to address the potential health risks for the local population consuming fish resources. The fish species were sampled between the Petran and Kelcyra sites during spring and autumn 2024, with analyses conducted on the concentrations of six heavy metals in muscle tissue and liver. Two instrumental techniques were used for these analyses: atomic absorption spectrophotometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS). The results were analyzed using SPSS software version 30.

Reproductive characteristics of mackerel scad Decapterus macarellus (Cuvier, 1833) in northern Philippine waters

Wed, 31 Dec 2025 00:00:00 GMT

Mackerel scad Decapterus macarellus is a highly valuable species in the Philippines municipal and commercial fishing industry, particularly in northern Philippine waters in the Babuyan Channel fishing ground. The study assesses reproductive characteristics, including the sex ratio, catch seasonality, fecundity, gonadosomatic index (GSI), gonad and sexual maturity (Lm and L95), and length range distribution by gear. Samples were collected in the Babuyan Channel fishing ground from April 2018 to March 2020. The results showed that D. macarellus is present throughout the year in the fishing ground, with noted peaks from April to July. An unbalanced sex ratio was found between the females (1:18) and males (1). The mean fecundity was 25,546 eggs. The gonadosomatic index revealed that the spawning season of D. macarellus occurs throughout the year, with an observed prolonged spawning and a notable peak during the northeast monsoon. The length at maturity (Lm) was 14.15 cm, and L95 was 17.60 cm. Of all the fishing gear for catching the species, beach seines catch most of the juveniles. Management options such as establishing additional Marine Protected Areas to support fish populations and productivity of the species, and reducing fishing effort are recommended to protect and conserve the stock.

Apparent Consumption of Salmonid Fish Products in Croatia from 2013 to 2023

Thu, 04 Sep 2025 00:00:00 GMT

By estimating food and nutrient consumption national and international bodies organizations and scientific institutions gain critical insights into consumption patterns. These insights, spanning from global to household levels, are essential for guiding effective food, agricultural, management and market policies and strategies in both the public and private sectors. This paper applies Food Balance Sheets to analyse official data on domestic production and trade (imports and exports), presenting the apparent consumption (net supply and per capita) of salmonid products in Croatia for the period from 2013 to 2023. During this period, the average net supply of salmonid products was 2.078 tonnes live weight. The main product categories were fresh/chilled salmonids, salmonid fillets and smoked salmonid fillets, while frozen, prepared and preserved salmonids had a lower market share. The average per capita consumption was 0.51 kg live weight. Salmonids accounted for approximately 2.5% of the total apparent consumption of fishery and aquaculture products in Croatia. In order to improve consumer awareness, the public sector should develop targeted and effective food and agricultural policies and optimize data collection related to processing. production and trade in cooperation with the private sector. Meanwhile, the private sector should increase production, expand product diversification (including filleting and smoking) and strengthen marketing initiatives.

Effects of External Calcium Concentrations on Calcium uptake in Freshwater Snail Planorbarius Corneus L.

Thu, 04 Sep 2025 00:00:00 GMT

Calcium content of water is of fundamental importance for freshwater snails since it is correlated with growth rates, egg fertility and fecundity. In this study, calcium uptake from the external medium (tap water) in two groups of freshwater snail Planorbarius corneus L. was compared: 200 control snails permanently maintained in tap water, and 200 experimental snails exposed to solutions with high calcium concentrations (214–2137 mg/L) for six weeks before the measurements. The results showed higher uptake in control snails (0.8 mg Ca2+ per snail/day) than in experimental snails (0.4 mg Ca2+ per snail per day), P<0.001. Measurements of Ca2+ in shells and tissues showed a higher calcium content in experimental snails than in control snails, both in the shells (P<0.02) and in the tissue (P<0.05). Lower shell/tissue calcium ratio and lower organic mass loss by ashing showed that experimental snails stored 1.5 times more Ca2+ in soft tissues compared with control snails. Empty dry shells of the control snails accounted for 27% of the total body mass, and in the experimental snails, shell mass was 34% of the body mass. The results suggest that the lower uptake by experimental snails was caused by previously accumulated high quantities of calcium in shells and soft tissues. These findings enhance our understanding of calcium homeostasis in freshwater gastropods and indicate their adaptability to environments with fluctuating calcium levels.

Investigating the Diversity of Sea Urchins (Echinoidea) in Yogyakarta, Indonesia using Molecular Approaches, Abundance, and Ecological Index

Thu, 04 Sep 2025 00:00:00 GMT

Sea urchins are invertebrates playing a crucial ecological role in maintaining a balance within intertidal ecosystems and serve as bioindicators, in addition to their significant economic value as marine resources. This study aims to investigate sea urchins at Ngrumput Beach, Yogyakarta through ecological index analysis, abundance measurements, and morphological and molecular identification using the DNA barcoding approach. Sampling was from November to December 2023, using a 1x1 m quadrat transect method. Molecular identification targeted the mitochondrial DNA cytochrome oxidase subunit I (mtDNA COI) gene. On the basis of morphological and molecular identification, the identified sea urchin species were Echinometra oblonga, Echinometra mathaei, Heterocentrotus trigonarius, and Stomopneustes variolaris. The results indicated that the sea urchins at Ngrumput Beach had an abundance of 74.14 individuals/m2, a species diversity index of 1.07 (moderate), an evenness index of 0.83 (high), and a dominance index of 0.23 (low). Distribution pattern analysis revealed that Echinometra oblonga and Stomopneustes variolaris exhibited clumped distributions, while Heterocentrotus trigonarius and Echinometra mathaei displayed both uniform and clumped distributions. The highest sea urchin abundance was observed 30 meters from the shoreline. Molecular identification revealed a DNA sequence length of 630 bp. DNA barcoding analysis, including phylogenetic tree construction using the neighbour-joining method and genetic distance evaluation, supported the morphological analysis results.

Ecological Assessment of the Dabar River (Sanski Most): Implications for Conservation and Management

Thu, 04 Sep 2025 00:00:00 GMT

This study presents the first comprehensive ecological assessment of the Dabar River, a small karstic watercourse in the Sanski Most area, using biological indicators focusing on the macrozoobenthos community, microbiological parameters, and ichthyofaunal composition. Sampling was conducted at three sites (headwaters, middle course, and downstream section), applying standard methods for the analysis of macrozoobenthos composition, bacterial abundance (including Escherichia coli), and biological indices (SI, BMWP, ASPT, EBI). The results indicate a good ecological status of the river, particularly in the headwater section, with a slight decline in water quality downstream. A rich and stable benthic fauna was identified, dominated by Gammarus fossarum, Sadleriana fluminensis, and representatives of the EPT groups. Microbiological findings revealed low to moderate levels of contamination, with no presence of fecal bacteria. Dabarska Cave, which hosts endemic subterranean crustaceans and olm Proteus anguinus, represents a particular ecological value of the area. Guidelines for conservation and sustainable management are proposed, including legal protection of the watercourse, pollution control, and the development of ecotourism.

Probiotic Potential of Coral Microbiota: A Natural Defence against White Syndrome

Thu, 04 Sep 2025 00:00:00 GMT

Healthy coral-associated bacteria produce antimicrobial compounds that can inhibit disease-causing pathogens. This biocontrol potential is particularly relevant in combating White Syndrome (WS), a deadly coral disease. This study aimed to identify beneficial bacteria from healthy corals that could serve as WS control agents. Healthy and WS-infected coral samples were collected from Sawopudo waters, Southeast Sulawesi, Indonesia. Bacteria were isolated using spread and streak plate techniques, and their antibacterial activity was assessed in vitro via agar plug assays. Isolates with strong inhibition zones were identified by 16S rRNA gene sequencing. The most promising strains were tested in vivo by inoculating WS-infected corals with candidate bacteria. Of six isolates with notable antimicrobial activity, the most active showed high similarity to Bacillus tequilensis, Micrococcus luteus, Cytobacillus firmus, Staphylococcus arlettae, and Priestia aryabhattai (similarity 99.43%–99.93%). Cytobacillus firmus demonstrated the strongest in vivo efficacy, forming a 16.6 mm inhibition zone and restoring up to 20% of infected coral tissue. These results underscore the potential of probiotic bacteria as a sustainable strategy to mitigate WS and protect coral reef ecosystems.

Catch Assessment of Marine Fishes in Cabalian Bay, Philippines: Composition, Abundance, Gear, and Catch Rate

Tue, 27 May 2025 00:00:00 GMT

Marine fisheries play a crucial role in food security and livelihoods but face challenges from overfishing and environmental changes. This study assessed fish composition, abundance, fishing gear usage, and catch per unit effort (CPUE) at three key landing sites in Cabalian Bay, Philippines. Seventy-three fish species from 31 families were recorded, with the dominance of Carangidae (11%) and Scombridae (10%). Monthly fish catch data reveal fluctuations in fish abundance, with Scombridae consistently recording the highest catches, particularly in August, December, and January. Hook-and-line and gill net were the primary gear used with varying effectiveness across the landing sites. Simple handline (pasol) was the most widely used gear. Tawa recorded the highest CPUE in Pong-oy, while other gear remained consistently low across all months. These findings provide essential baseline data to support fisheries management and small-scale fishers. The study highlighted the need for strengthened marine protected areas and more sustainable fishing strategies to mitigate declining fish stocks and ensure the long-term sustainability of resources.

Discrimination of Morphological Traits Between Atlantic and Danubian Brown Trout Lineages and Their Hybrids

Tue, 27 May 2025 00:00:00 GMT

Brown trout of non-native lineages (e.g. Atlantic) have been stocked into Croatian streams and rivers primarily to meet angling demand, resulting in the presence of admixed populations at many locations. The clear, easily distinguishable morphological differences between the brown trout of the introduced Atlantic (AT) and indigenous Danubian (DA) lineages, as well as their hybrids (HY), were unknown. Therefore, the aim of this study was to identify classical morphometric and meristic traits that differentiate them. Brown trout were collected by electrofishing in ten streams from three mountain areas (Gorski Kotar, Mt. Žumberak and Mt. Papuk) during 2017 and 2018. Additionally, 10 specimens belonging to the AT lineage were obtained from a fish farm in continental Croatia. In total, 90 fish specimens were analysed: 17, 22 and 51 specimens of AT, DA and HY, respectively. The results revealed the most prominent differences in the head features of the AT compared to the DA lineage and their HY. Discriminant analysis demonstrated that eye diameter and postorbital length were significantly smaller, whereas interorbital width and head height were significantly larger in the AT lineage. These findings suggest the need for a detailed head morphometry analysis to identify distinctive morphological traits that differentiate brown trout lineages and detect their hybrids.

Assessment of Water Quality of the Gostelja River Based on the Composition of Macrozoobenthos Communities

Tue, 27 May 2025 00:00:00 GMT

The collection of macrozoobenthos from the Gostelja River was conducted in May 2022. Sampling was carried out at 7 locations. Through qualitative-quantitative analysis of macrozoobenthos, a total of 19 taxa or 355 individuals belonging to different taxonomic groups such as Mollusca, Turbellaria, Ephemeroptera, Plecoptera, Trichoptera, Diptera, and Odonata were recorded. Based on the conducted research and index calculations, we can conclude that different water quality classes can be observed along the course of the Gostelja River.

Organic Material Solubility and Dynamic Modelling Analysis of Intensive Shrimp Farming Activities in the Coastal Area of Pekalongan, Indonesia

Tue, 27 May 2025 00:00:00 GMT

The interaction between water and soil quality in intensive shrimp farming significantly influences the success of aquaculture operations. This study aims to examine the correlation between fluctuations in water and soil quality in intensive shrimp ponds and analyze the solubility level of organic matter using a dynamic system modelling approach. The research method used a causal ex post facto design, collecting data systematically from intensive shrimp ponds. The findings indicate that increased shrimp growth stimulates higher feeding activity, which subsequently raises waste production and organic matter solubility within the pond ecosystem. Over time, this process reaches a saturation point. By the fifteenth week of the operational cycle, the pond’s waste carrying capacity decreases, ultimately affecting shrimp farming productivity patterns. Throughout the farming cycle, fluctuations in water and soil quality parameters demonstrate this dynamic interaction. The study identifies a strong correlation between these factors, with patterns following an oscillatory trend in the model. The ecosystem’s carrying capacity primarily depends on waste load levels, oxygen availability for organic matter absorption, and the overall condition of the aquatic environment. Organic matter solubility exhibits an accumulative pattern throughout the operational cycle, highlighting its crucial role in ecosystem dynamics. The study concludes that water and soil quality are inherently linked to the stability of the pond ecosystem. Additionally, the presence and distribution of organic matter, as revealed through dynamic modeling, serve as critical factors influencing the ecological balance in shrimp farming systems.

First Record of Northern Pike Esox lucius (Actinopterygii: Esociformes: Esocidae) in the Kuti Lake Area (Mala Neretva)

Tue, 27 May 2025 00:00:00 GMT

This paper describes the first record of northern pike Esox lucius (Linnaeus, 1758) in Kuti Lake (Mala Neretva, Croatia). A specimen of this species was caught in Kuti Lake in November 2024. The presence of pike has been recorded in tributaries and reservoirs of the Neretva River in Bosnia and Herzegovina, but its presence in the Neretva River system in Croatia presents an expansion of the distribution of the species. Although local fishermen and sources from grey literature in recent years indicate that this species is already present in the area where this specimen was caught, further research is needed to determine the mode of introduction and whether a stable population is present in the area.