In this paper are presented the length and weight growth of carp (Cyprinus carpio L.) from artificial lake Slatino (The Former Yugoslav Republic of Macedonia). Artificial lake Slatino because some recontruction works was whole emplied in 1993. Than all fish population was leaved in the river Mramorechka. Artificial lake Slatino has been stocking with individuals of carp (Cyprinus carpio L.) catch from Lake Ohrid. They are used for reproduction and in first years were used for reparation of the fish fond in artificial lake.

Hydrogen peroxide (H₂O₂), as a common disinfectant, has been extensively used in aquaculture. The toxicity of high ambient H₂O₂ for gills and liver of fish has received attention from many researchers. However, whether H₂O₂ exposure induced brain injury and neurotoxicity has not been reported in fish. Therefore, this study aimed to explore the potential mechanism of H₂O₂ toxicity in brain of common carp via transcriptome analysis and biochemical parameter detection. The fish were exposed to 0 (control) and 1 mM of H₂O₂ for 1 h per day lasting 14 days. The results showed that H₂O₂ exposure caused oxidative damage in brain evidenced by decreased glutathione (GSH), total antioxidant capacity (T-AOC) and nicotinamide adenine dinucleotide (NAD⁺) levels, and increased formation of malondialdehyde (MDA) and 8-hydroxy-2′-deoxyguanosine (8-OHdG). Meanwhile, H₂O₂ exposure reduced 5-hydroxytryptamine (5-HT) level, and down-regulated tryptophan hydroxylase 1 (tph1a), tph2, 5-hydroxytryptamine receptor 1A-beta (htr1ab) and htr2b expression in brain. Transcriptome analysis showed that H₂O₂ exposure up-regulated 604 genes and down-regulated 1209 genes in brain. Go enrichment displayed that the differently expressed genes (DEGs) were enriched mainly in cellular process, single-organism process, metabolic process, and biological regulation in the biological process category. Further, KEGG enrichment indicated that H₂O₂ exposure led to dysregulation of neurotransmitter signals including depression of glutamatergic synapse, GABAergic synapse and endocannabinoid signaling. Also, we found the alteration of three key pathways including calcium, cAMP and HIF-1 in brain after H₂O₂ exposure. In conclusion, our data indicated that H₂O₂ exposure induced oxidative damage and neurotoxicity, possibly related to dysregulation of neurotransmitters and calcium, cAMP and HIF-1 signaling pathways, which may adversely affect learning, memory and social responses of common carp. This study provided novel insight into biological effects and underlying mechanism of H₂O₂ toxicity in aquatic animal, and contributed to proper application of H₂O₂ in aquaculture.

Trichlorfon is an organic phosphorus pesticide used to control different parasitic infections in aquaculture. The repeated, excessive use of trichlorfon can result in environmental pollution, thus affecting human health. This study aimed to determine the effects of different concentrations of trichlorfon (0, 0.1, 0.5 and 1.0 mg/L) on the intestinal barrier, oxidative stress, inflammatory response and intestinal microbiome of common carp. Trichlorfon exposure significantly reduced the height of intestinal villus and decreased the expression levels of tight junction genes, such as claudin-2, occludin and ZO-1, in common carp. Moreover, the activities of antioxidant enzymes, such as CAT, SOD and GSH-Px, exhibited a decreasing trend with increasing trichlorfon concentrations, while the contents of MDA and ROS elevated in the intestinal tissues of common carp. The mRNA and protein levels of pro-inflammatory cytokines TNF-α and IL-1β were significantly upregulated by trichlorfon exposure. The level of anti-inflammatory cytokine TGF-β was remarkably higher in 1.0 mg/L trichlorfon treatment group compared to control group. In addition, the results demonstrated that trichlorfon exposure could affect the microbiota community composition and decreased the community diversity in the gut of common carp. Notably, the proportions of some probiotic bacteria, namely, Lactobacillus, Bifidobacterium and Akkermansia, were observed to be reduced after trichlorfon exposure. In summary, the findings of this study indicate that exposure to different concentrations of trichlorfon can damage intestinal barrier, induce intestinal oxidative damage, trigger inflammatory reaction and alter gut microbiota structure in common carp.

Although the toxicity of silver nanoparticles (AgNPs) in aquatic organisms has been extensively investigated, the mechanism by which AgNPs damage membranes remains unclear. This study investigated the toxic effects of a series of sub-lethal concentrations of AgNPs on the membranes of freshwater carp (Cyprinus carpio) gills, based on changes in membrane fatty acid (FA) profile, membrane fluidity, membrane lipid peroxidation, and histopathology. Most of the FAs in fish gill membrane was not significantly affected by exposure to multiple AgNPs concentrations, only few significant changes occurred in some specific FAs species at a high concentration of AgNPs exposure. In particular, high concentrations of AgNPs significantly decreased the proportions of two important long-chain n-3 series polyunsaturated FAs (C20: 5n3, and C22: 6n3), resulting in a decreased ratio of n-3 polyunsaturated FAs to n-6 polyunsaturated FAs (Σn-3UFA/Σn-6UFA). The AgNPs also caused a dose-dependent decrease in fish gill membrane fluidity, increased the level of lipid peroxidation, and inhibited Na+/K+-ATPase enzyme activity. Further histopathological examination revealed that exposure to AgNPs can cause toxic responses in the lamellae, including the thinning of the basement membrane, malformation, and inflammation. Together, the results suggest that the mechanism of AgNPs membrane toxicity involves the oxidization of long-chain omega-3 unsaturated FAs to saturated FAs via lipid peroxidation, resulting in, decreased membrane fluidity and ultimately the destruction of the normal physiological function of the fish gill membrane. The findings contribute significantly to our understanding of nanoparticle-induced membrane toxicity and potential risks in aquatic environments.

Differences in the toxicological and metabolic pathway of inorganic arsenic compounds are largely unknown for aquatic species. In the present study the effects of short-time and acute exposure to AsIII and AsV were investigated in gills and liver of the common carp, Cyprinus carpio (Cyprinidae), measuring accumulation and chemical speciation of arsenic, and the activity of glutathione-S-transferase omega (GST Ω), the rate limiting enzyme in biotransformation of inorganic arsenic. Oxidative biomarkers included antioxidant defenses (total glutathione-S-transferases, glutathione reductase, glutathione, and glucose-6-phosphate dehydrogenase), total scavenging capacity toward peroxyl radicals, reactive oxygen species (ROS) measurement and lipid peroxidation products. A marked accumulation of arsenic was observed only in gills of carps exposed to 1000 ppb AsV. Also in gills, antioxidant responses were mostly modulated through a significant induction of glucose-6-phosphate dehydrogenase activity which probably contributed to reduce ROS formation; however this increase was not sufficient to prevent lipid peroxidation. No changes in metal content were measured in liver of exposed carps, characterized by lower activity of GST Ω compared to gills. On the other hand, glutathione metabolism was more sensitive in liver tissue, where a significant inhibition of glutathione reductase was concomitant with increased levels of glutathione and higher total antioxidant capacity toward peroxyl radicals, thus preventing lipid peroxidation and ROS production. The overall results of this study indicated that exposure of C. carpio to AsIII and AsV can induce different responses in gills and liver of this aquatic organism. Common carp (Cyprinus carpio) presented marked differences between gills and liver after arsenic exposure in terms of antioxidant responses and also in biotransformation.

In this study, the influence of the co-existence of TiO2 nanoparticles on the speciation of arsenite [As(III)] was studied by observing its adsorption and valence changing. Moreover, the influence of TiO2 nanoparticles on the bioavailability of As(III) was examined by bioaccumulation test using carp (Cyprinus carpio). The results showed that TiO2 nanoparticles have a significant adsorption capacity for As (III). Equilibrium was established within 30 min, with about 30% of the initial As (III) being adsorbed onto TiO2 nanoparticles. Most of aqueous As (III) was oxidized to As(V) in the presence of TiO2 nanoparticles under sunlight. The carp accumulated considerably more As in the presence of TiO2 nanoparticles than in the absence of TiO2 nanoparticles, and after 25-day exposure, As concentration in carp increased by 44%. Accumulation of As in viscera, gills and muscle of the carp was significantly enhanced by the presence of TiO2 nanoparticles. The co-existence of TiO2 nanoparticles could change the speciation of arsenite by adsorption and photo-oxidation, and enhance its bioaccumulation to carp.

Freshwater environments are more sensitive to anthropogenic influences and usually contain higher concentrations of pollutants than marine environments. Microplastic pollution causes additional stress on freshwater animals; yet, studies evaluating the microplastic occurrence in freshwater biota are still limited. In this study, microplastic occurrence in the gastrointestinal tracts (GIT) and gill of commercial fish species (Prussian carp Carassius gibelio (Bloch, 1782); Abu mullet Planiliza abu (Heckel, 1843); Common carp Cyprinus carpio Linnaeus, 1758; European ell Anguilla Anguilla (Linnaeus, 1758); North African catfish Clarias gariepinus (Burchell, 1822); Goldfish Carassius auratus (Linnaeus, 1758) were reported from Orontes River. MPs abundance in the GIT and gill of six species were found as 5.1 ± 2 MPs fish⁻¹ and 4.4 ± 2 MPs fish⁻¹ with an occurrence of 95% and 74%, respectively. The majority of extracted microplastics were fiber, black and less than 1000 μm in size. FTIR analysis determined the main polymer types as polyester (50%), high-density polyethylene (HDPE) (10%), polypropylene (PP) (8%) and polyethylene terephthalate (PET) (5%). High MPs abundance and frequency of occurence indicate the exposure of microplastic pollution in freshwater biota which could threat the health of both individuals and consumers. Results obtained in this study will increase the acknowledgement of MPs pollution in the Orontes River. Also, this study will provide data to the administrators to set up necessary legislations in freshwater ecosystems.

Antibiotics are emerging pollutants in our environment. These treatments have been widely used for their low cost, convenient use, and prominent effects. However, the prolonged or excessive use of such drugs can cause toxicity in aquatic organisms. These effects include genotoxicity, metabolic alteration, delayed development and decreased immunity, which carry further risks for ecological systems. In the present study, juvenile common carp (Cyprinus carpio) were exposed to norfloxacin (NOR) for 42 days, with NOR concentrations ranging from 100 ng/L to 1 mg/L, to assess the effects of environmental concentrations of antibiotics, to investigate the effects of NOR on intestinal morphology, enzymatic activity, and transcriptomic levels of RNA in fish, as well as a risk assessment on human health was carried out. The results demonstrated that oxidative stress was induced, the barrier function of the intestine was damaged, and changes occurred in the expression of immune-related genes in fish chronically exposed to antibiotics. Moreover, NOR could affect the regulation of the NF-κB signaling pathway. Thus, environmental concentrations of antibiotics can influence the intestinal health of fish and potentially posing health risks to humans.

Fluorine, an environmental toxicant in our daily life, has been reported to have adverse effects on nervous system. Previous studies demonstrated that fluorine exposure could induce brain injury in fish and human. However, the possible mechanism remains unclear. In the present study, we aimed to reveal the mechanism of fluorine exposure on brain injury of common carp through transcriptome analysis. In the fluorine-exposed carp, 444 brain genes were up-regulated, whereas 742 genes were down-regulated. DNA-templated (regulation of transcription) and multicellular organism development in the GO function annotation accounted for the most biological processes. Nucleus and membrane accounted for the most cellular components and DNA binding and metal ion binding accounted for the most molecular function. Meanwhile, 196 metabolic pathways were identified in Kyoto Encyclopedia of Genes and Genomes (KEGG) Pathway significant enrichment analysis, including long-term depression, Cushing syndrome, nuclear receptors, vascular smooth muscle contraction, Ion channels, and other pathways. Furthermore, we found that the up-regulated and down-regulated trends were similar between the quantitative real-time-PCR and RNA-Seq results, which indicate the transcriptome sequencing data is reliable. In conclusion, our data may provide insights into the mechanisms underlying brain injury induced by fluorine exposure.

With increasing demand for aquaculture products, water reuse is likely to increase for aquaculture operations around the world. Herein, wastewater stabilization ponds (WSP) represents low cost and sustainable treatment technologies to reduce nutrients and various contaminants of emerging concern from effluent. In the present study, we examined bioaccumulation of selected pharmaceuticals from several therapeutic classes by two important fish species in aquaculture with different feeding preferences (Cyprinus carpio and Sander lucioperca) and their common prey to test whether species specific accumulation occurs. Forty and nineteen from 66 selected pharmaceuticals and their metabolites were positively found in water and sediment samples, respectively from the representative WSP. After a six-month study, which corresponds to aquaculture operations, fourteen pharmaceuticals and their metabolites were detected (at a frequency of higher than 50% of samples) in at least one fish tissue collected from the WSP. We observed striking differences for species and organ specific BAFs among study compounds. Though muscle tissues consistently accumulated lower levels of the target analytes, several substances were elevated in brain, liver and kidney tissues (e.g., sertraline) of both species. Low residual concentrations of these target analytes in aquaculture products (fish fillets) suggest WSPs are promising to support the water-food nexus in aquaculture.