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Blood analysis is used to evaluate the effects of various environmental factors on fishes and to assess fish health and welfare. Fish blood is routinely sampled from the caudal vein or the heart. The aim of the present study was to determine the differences between venous and cardiac crucian carp (Carassius carassius (L.)) blood parameters. Additionally, the influence of sex was tested. The fish were divided into two groups: group I consisted of 10 males and 9 females, group II consisted of 8 males and 8 females. The fish from group I had blood sampled first from the caudal vein and then from the heart. The fish from group II had the procedures in the opposite order. The hematological parameters determined in the present study depended on the blood collection site and the sex of the individuals. Blood biochemical indices depended on the sex of the fish but not on the blood sampling site. The effect of sampling order was observed in the case of both hematological and biochemical parameters. The results of the current study indicated that the blood collection site, the sex of fish, and sampling order should be taken into consideration in hematological experiments.

Abstract Mercury is one of the important pollutants of the environment. Therefore, it’s necessary to monitor quantity of mercury especially in aquatic ecosystems. The main goal of the presented study was to compare the content of total mercury in tissues of fish coming from the Czech Republic, an important carp exporter, with focus on comparison of mercury content between 3 different ponds, its comparison between different fish species and between different tissues of the same species, and estimation whether the mercury content in tissues meets the limit given in the Commission Regulation (EC) No. 1881/2006 or not. Total mercury concentration was measured in 90 fish specimen sampled from three ponds (Velky Kocelovicky, Mysliv and Zehunsky) in autumn 2018. The values of total mercury in fish tissues was measured by atomic absorption spectrometry. The content of total mercury in the tissues decreased as follows: muscle > liver > gonads > scales. The highest average content of total mercury in muscle was 0.1517 ± 0.0176 mg/kg coming from pike caught in Velky Kocelovicky pond. In contrast, the lowest average content of total mercury in muscle 0.0036 ± 0.0003 mg/kg was found in carp tissue coming from the locality of Zehunsky pond. We confirmed that the predatory fish are more exposed to mercury than non-predatory fish. None of the monitored localities exceeded the set regulatory limit. Thus, our study shows that fish coming from these ponds are safe in terms of total mercury content.

At present, the assessment of pig welfare quality has gained significant importance, prompting the exploration of novel biomarkers for this purpose. Traditionally, these biomarkers have been monitored in the blood; however, blood sampling is considered an invasive procedure. Currently, non-invasive methods for collecting samples are emerging as viable alternatives for assessing these biomarkers. This article aims to present the current knowledge regarding the use of non-invasive methods for analysing pig welfare biomarkers, specifically focusing on the saliva, hair, faeces, and urine as matrices to determine these biomarkers. The saliva analysis encompasses various biomarkers, such as cortisol, alpha-amylase, chromogranin A, the total esterase, oxytocin, acute phase proteins, adenosine deaminase, immunoglobulins and parameters of redox homeostasis. Cortisol, a specific biomarker, can be determined in the hair, urine and faeces, while urine samples allow for the analysis of catecholamines as non-invasive markers of pig welfare. [ABSTRACT FROM AUTHOR]

The growing consumption of pharmaceuticals in the human population and the insufficient efficiency of their elimination in waste water has a long-term negative impact on the environment of aquatic ecosystems, including the organisms that inhabit them. A significant contributor is the consumption of antidepressants from the SSRI group, which corresponds to their increasing concentration in the environment. The aim of this work was to determine if antidepressant sertraline is able to be stored in fish organisms and to evaluate the content of residues in various body tissues. Rainbow trout ( Oncorhynchuss mykkis) was selected as the test organism and was artificially exposed to the antidepressant for 1 month (concentrations 0; 4.2; 44 and 400 ng.g-1 sertraline in the feed). Liver, kidney, brain and muscle tissue biopsies samples were taken for analysis. Detection was performed using an Accela 1250 LC pump and an Accela autosampler coupled with a high-performance mass analyzer with a heated electrospray ionization source Q-Exactive Orbitrap, operating in positive ionization mode and in PRM mode (m/z 306.08108→275.03888 and 309.009991→275.03888 for sertraline and internal standard, respectively). The limit of quantification of the method was 0.1 ng.g-1 of sertraline and the calibration curve showed a good linearity up to 20 ng.g-1. From the collected data, amount of residues was found in the liver, kidney and brain. In contrast, the incidence of residues in muscle tissue was not detected in all groups, which is favorable from the point of view of fish meat consumption, by humans. [ABSTRACT FROM AUTHOR]

The level of contamination of the aquatic environment with residues of drugs as metoprolol, enalapril and metformin is constantly increasing. One of the reasons is the increasing prescribes and uses of these drugs, second is imperfect purification in wastewater treatment plants. Since the pharmaceuticals are entering water bodies continuously, they represent a potential risk for non-target aquatic biota. In our study, the toxicity of metformin, metoprolol and enalapril on zebrafish (Danio rerio) embryos in five different concentrations was tested. The acute toxicity test was performed according to OECD Guideline No. 236: Fish Embryo Acute Toxicity Test. The aim of this experiment was to study toxic effects of typical drugs used for treatment of diseases of affluence as diabetes, cardiovascular diseases and hypertension on fish early life stages. Metformin is the most common drug used to treat type II. diabetes, metoprolol and enalapril are used to treat diseases of the cardiovascular system and hypertension. The results showed that the tested substances had a negative effect on hatching of embryos at all tested concentrations and also they have influenced mortality and heartbeat. [ABSTRACT FROM AUTHOR]

Plastic pollution is a global problem caused by an excessive use of this material, its high resistance in the environment and poor waste management. In the environment, larger-sized plastic particles may be transformed into smaller particles, so-called microplastics (< 5 mm), which have been discovered in the bodies of various organisms, across all trophic levels of the aquatic environment (Provencher et al., 2017). Effects of microplastics on fish embryos are described as malformations, changes in behavior and swimming ability, early hatching, increased mortality and decreased heart rate (Bhagat et al., 2020). However, these negative effects must be interpreted based on environmental concentrations in water sources (0.0001 - 2 mg/L; Rodrigues et al., 2022), which leads to uncertainties when carrying out ecological risk assessment on these particles. In our experiment, the effect of polystyrene microspheres (50 μm) on zebrafish embryos was tested in three concentrations - 0.001, 0.005 and 0.01% of solution for 96 hours with 18 eggs of zebrafish (Danio rerio) per each concentration. The plates were kept in a temperature-controlled test environment (26 °C) with a photoperiod of 12 h light/12 h dark. Testing solutions were replaced every day to make sure that the test concentrations remained their nominal values. During the test, each plate was checked for coagulation of fertilized eggs, lack of somite formation, lack of detachment of tail-bud from the yolk sack, lack of the heartbeat, hatching rate and developmental malformations. After 96 h exposure, 8 replicates were crated from each test group, with each sample containing 10 mg of embryos to subsequent PCR analysis of selected genes and proteomic to the systematic identification and quantification of selected proteins. The significant changes at tested concentrations were compared to control group, without microplastic addition. [ABSTRACT FROM AUTHOR]

Objectives: We tested the toxicity of ethinylestradiol, a semisynthetic estrogen used in oral contraceptives, on all-male triploid zebrafish using commercial feeds and three different doses concentrations. We aimed to determine whether ethinylestradiol peroral administration resulted in vitellogenin production and whether all-male triploid zebrafish could serve as a model species for xenoestrogen testing., Methods: The actual concentrations of 17α-ethinylestradiol were 0.0035 (low); 0.0315 (medium) and 0.365 (high) µg/g. Positive control represented commercial feeds containing 0.0465 µg/g of β-estradiol. The experiment lasted 8 weeks., Results: Our results indicate that 17α-ethinylestradiol consumption does induce vitellogenin production in triploid zebrafish., Conclusions: The simple presence of vitellogenin is a definite symptom indicative of the potential for such changes due to the action of estrogenic substances. As such, this experiment has shown that the use of all-male triploid zebrafish populations, rather than the mixed-sex populations of other species previously used, could serve as a suitable alternative model population for controlled testing of the effects of xenoestrogens on fish.