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Fish are excellent bioindicators and can reveal the presence of plastic in the environment. Diagnosing the composition and abundance of polymers in the fish diet makes it possible to evaluate their point sources and possible trophic transfers. We aimed to use the gastrointestinal contents of Poecilia reticulata in subtropical urban streams to detect the occurrence, shape, color, size, and chemical composition of polymers. For this, the diet of 240 individuals was analyzed using the volumetric method, and the microplastics (MPs; < 5 mm) recorded were characterized using Raman spectroscopy. Individuals predominantly consumed organic detritus and aquatic macroinvertebrates, with higher proportions of Diptera. A total of 111 plastic particles (< 0.5 to 12 mm) were recorded, and a subset of 14.4% was subjected to a micro-Raman spectrometer (830 nm excitation). The occurrence of polyethylene terephthalate (PET) and polypropylene (PP) with phthalocyanine dye was recorded. Some fragments could not be identified by Raman, but they contained indigo blue dye. Poecilia reticulata had a predominantly detritivorous diet with a record of plastic consumption, reflecting environmental pollution. Our results demonstrate that individuals of P. reticulata have ingested MPs in urban streams. This reinforces the need for future studies on the relationship between the presence of MPs in fish and the level of pollution in streams, comparisons with species of different feeding habits, and the potentially harmful effects on the entire biota.

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Since 2019, the Brazilian Institute of Environment and Renewable Natural Resources (IBAMA) has actively developed pesticide environmental risk assessment (ERA) frameworks adapted to Brazil's specific ecological contexts. This endeavor, supported by funding from the Brazilian Ministry of Justice and in partnership with academic institutions, has led to a concerted effort to establish ERA protocols for various taxa, including birds and mammals, soil organisms, aquatic organisms, and reptiles and amphibians. The outcomes of this initiative were conveyed in two workshops held in February and November 2023, during which the agency communicated its findings to the technical-regulatory community. This article represents one of three articles that provide more detailed insights into the ERA propositions for all taxa. In this article, we summarize the proposals for aquatic organisms presented and discussed during the workshops, which can be used as an informational source by the technical-regulatory community. Integr Environ Assess Manag 2024;00:1-6. © 2024 The Author(s). Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

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This study evaluated the anesthetic and sedative effects of the essential oil of Zingiber officinale (EOZO) on juvenile pacu (Piaractus mesopotamicus). Experiment 1 evaluated concentrations of 0, 50, 100, 200 and 400 mg L-1 EOZO for times of induction and recovery from anesthesia. Furthermore, hematological responses and residual components of EOZO in plasma were determined immediately after anesthesia. Experiment 2 evaluated the effect of 0, 10, 20 and 30 mg L-1 EOZO on water quality, blood variables and residual components of EOZO in plasma and tissues (muscle and liver) immediately after 2 h of transport. Survival was 100%. The three main compounds of EOZO [zingiberene (32.27%), ß-sesquiphellandrene (18.42%) and ß-bisabolene (13.93%)] were observed in animal plasma and tissues (muscle and liver) after anesthesia and transport, demonstrating a direct linear effect among the evaluated concentrations. The concentration of 200 mg L-1 EOZO promoted surgical anesthesia of pacu and prevented an increase in monocyte and neutrophil levels, yet did not alter other hematological parameters. The use of 30 mg L-1 EOZO has a sedative effect on juvenile pacu, thereby reducing oxygen consumption during transport. Furthermore, the use of 30 mg L-1 EOZO in transport water prevented an increase in hemoglobin and hematocrit, with minimal influences on other blood variables.

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Pimelodus is the most speciose genus of the family Pimelodidae, and is amply distributed in the Neotropical region. The species-level taxonomy and phylogenetic relationships within this genus are still poorly resolved, however. These taxonomic problems and the general lack of data have generated major uncertainties with regard to the identification of specimens from different localities. In the present study, we applied a single-locus species delimitation approach to identify the MOTUs found within the genus Pimelodus and provide sound evidence for the evaluation of the species richness of this genus in the different river basins of the Neotropical region. The study was based on the analysis of sequences of the mitochondrial COI gene of 13 nominal species, which resulted in the identification of 24 consensus MOTUs. Only six nominal species were recovered as well-defined molecular entities by both the traditional barcoding analysis and the molecular delimitation methods, while the other seven presented cryptic diversity or persistent taxonomic uncertainties. The lineages identified from the Parnaíba ecoregions, Amazonas Estuary and Coastal Drainages may represent a much greater diversity of Pimelodus species than that recognized currently, although a more detailed study of this diversity will be necessary to provide a more definitive classification of the genus.

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This study aimed to assess the growth of Pseudomonas spp. and psychrotrophic bacteria in chilled Pacu (Piaractus mesopotamicus), a native South American fish, stored under chilling conditions (0 to 10 °C) through the use of predictive models under isothermal and non-isothermal conditions. Growth kinetic parameters, maximum growth rate (µmax, 1/h), lag time (tLag, h), and (Nmax, Log10 CFU/g) were estimated using the Baranyi and Roberts microbial growth model. Both kinetic parameters, growth rate and lag time, were significantly influenced by temperature (P < 0.05). The square root secondary model was used to describe the bacteria growth as a function of temperature. Secondary models, √µ = 0.016 (T + 10.13) and √µ =0.017 (T + 9.91) presented a linear correlation with R2 values >0.97 and were further validated under non-isothermal conditions. The model's performance was considered acceptable to predict the growth of Pseudomonas spp. and psychrotrophic bacteria in refrigerated Pacu fillets with bias and accuracy factors between 1.24 and 1.49 (fail-safe) and 1.45-1.49, respectively. Fish biomarkers and spoilage indicators were assessed during storage at 0, 4, and 10 °C. Volatile organic compounds, VOCs (1-hexanol, nonanal, octenol, and indicators 2-ethyl-1-hexanol) showed different behavior with storage time (P > 0.05). 1H NMR analysis confirmed increased enzymatic and microbial activity in Pacu fillets stored at 10 °C compared to 0 °C. The developed and validated models obtained in this study can be used as a tool for decision-making on the shelf-life and quality of refrigerated Pacu fillets stored under dynamic conditions from 0 to 10 °C.

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INTRODUCTION: Two new dactylogyrid monogeneans, Anacanthorus cultro n. sp. and Notozothecium palometae n. sp., are described based on specimens collected from the gill filaments of Mylossoma albiscopum (Cope, 1872) (Characiformes: Serrasalmidae), a pelagic and herbivore teleost collected in the Tigre river, Loreto, Peru. MATERIALS AND METHODS: Some monogeneans were stained with Gomori's trichrome and mounted in Canada Balsam to determine internal soft structures. Others were cleared in Hoyer's medium for the study of sclerotized structures. Drawings were made using a drawing tube and a microprojector. RESULTS: Anacanthorus cultro n. sp. is characterized by the presence of a rod-shaped male copulatory organ (MCO) lacking featherlike structures, and a knife-shaped accessory piece with a submedial knob. Notozothecium palometae n. sp. can be distinguished from all congeners by its MCO with a subbasal spur and an accessory piece with inverted hammer shaped. CONCLUSIONS: This is the first data on the parasites of M. albiscopum, a popular fish in local markets. Anacanthorus cultro n. sp. is the twenty-fifth documented species of the genus in Peru, while N. palometae n. sp. represents the seventh species of the genus known to infect freshwater fish species in Peru.

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The effects of thermal shock on hematological, biochemical and antioxidant responses were evaluated in liver tissue of juvenile tambaqui (Colossoma macropomum) and tambatinga (♀ C. macropomum × â™‚ Piaractus brachypomus). Forty juveniles of tambaqui and 40 juveniles of tambatinga, of the same age and with an initial weight of 23.3 ± 6.7 g, were randomly distributed in eight 28L circular tanks. A tank (n = 10 fish) of tambaqui and a tank (n = 10 fish) of tambatinga were then used to obtain basal data. The other animals were subjected to thermal shock with sudden temperature reduction from 28 to 18 ºC. Blood and tissue were then collected after 1, 6 and 24 h from the onset of thermal shock. No mortality was observed during the experimental period. Thermal shock increased triglyceride levels after 24 h of stress for tambaqui and reduced values for tambatinga. There was an effect on plasma glucose only for fish group (P < 0.0001) and collection time (P < 0.0001) with a peak observed for the hybrid after 6 h. The interaction of factors for SOD indicated greater activity for tambatinga at the 6 h collection and lower at basal and 1 h collections. There was an interaction for CAT (P = 0.0020) with less activity for tambatinga at 1 h. However, thermal shock and hybridization did not influence GST and TBARS levels in liver tissue. Therefore, the results suggest that the hybrid, tambatinga, is more efficient at promoting adjustments of biochemical responses and antioxidant enzymes during thermal shock.

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Bioaccumulation studies in fish mark the initial phase of assessing the risk of chemical exposure to biota and human populations. The Iguaçu River boasting a diverse endemic ichthyofauna, is grappling with the repercussions of human activities. This study delved into the bioaccumulation of micropollutants, the early-warning effects on Rhamdia quelen and Oreochomis niloticus in the Segredo Reservoir (HRS) and the potential risk of human exposure. Two groups of caged fish in three sites of the reservoir were exposed during the autumn-winter and spring-summer, while a third group (O. niloticus) underwent a twelve-month exposure, and inorganic and organic chemicals analysis in water, sediment, and biota. Additionally, metallothionein expression and genotoxicity were employed as biomarkers. PAHs, PCBs, Al, Cu, Fe, and As in water and DDTs, Cu, Zn, and As in sediment surpassed the thresholds set by Brazilian regulations, where DDT exhibited bioaccumulation in muscle, alongside metals in liver, kidney, gills, and muscle tissues. R. quelen showed metallothionein expression whereas DNA damage and NMA frequencies were elevated in target organs and in brain and erythrocytes of O. niloticus during summer. In this species the DNA damage in liver was remarkable after twelve months. Target Hazard Quotients and Cancer Risk values shedding light on the vulnerability of both children and adults. The reservoir's conditions led to heightened sensitivity to micropollutants for R. quelen species. The data presented herein provides decision-makers with pertinent insights to facilitate effective management and conservation initiatives within the Iguaçu Basin.

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With 76 currently valid species, the bushynose catfish genus Ancistrus is the fourth most species-rich catfish genus, yet Ancistrus diversity remains underestimated, with many species still undescribed. This is especially true of the Peruvian Andean headwaters of the Amazon, which are rich in unnamed Ancistrus species but have received little recent taxonomic attention. We describe a distinctively striped new Ancistrus species from tributaries of the Palcazú River, in the Pachitea-Ucayali-Amazonas drainage basin. The new species differs from all congeners by having black, vermiculated lines covering the head and two to four distinct black, parallel, lateral body stripes from head to caudal fin (vs. body uniformly colored or with dark or light spots or blotches over head and body, or black vermiculate lines on flanks). The new species is the fifth valid species of Ancistrus described from the rich Ucayali River ichthyofauna. It has previously been recognized in the aquarium fish trade as L267.

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Abstract Despite being an important component of the freshwater ecosystems and an important factor controlling wild fish populations, Amazonian fish parasites have been poorly studied. Here, we analyzed the fauna of metazoan parasites from 10 detritivorous and omnivorous fish species from Amapá Lake in the western Amazon. Of 159 fish specimens examined, 73.6% were parasitized by one or more species of metazoan parasites. A total of 5,260 parasites (24 Monogenea, 14 Nematoda, 10 Digenea, 2 Acanthocephala, and 6 Crustacea) were identified. Aggregated dispersion pattern of parasites was observed. There was a predominance of endohelminth species that presented a similar pattern regarding the level of component communities (i.e., a low species number, low diversity and dominance of a single species, mainly the digeneans and nematodes in their larval stages). Five species of parasites presented correlation with the body size of the hosts. In the fish community, the presence of endoparasites in the larval and adult stages suggests that these are intermediate, paratenic and definitive hosts, reflecting their detritivorous or omnivorous feeding habits. The trophic level and diet had an influence on the structuring of endohelminth communities and infracommunities. Lastly, 38% of the metazoan parasite species were new records for examined hosts.

Resumo Apesar de ser um importante componente dos ecossistemas de água doce e um importante fator controlador das populações naturais de peixes, os parasitos de peixes amazônicos ainda são pouco estudados. Foi analisada a fauna de parasitos metazoários em 10 espécies de peixes detritívoros e onívoros do Lago Amapá na Amazônia ocidental. Dos 159 espécimes de peixes examinados, 73,6% estavam parasitados por uma ou mais espécies de parasitos metazoários. Um total de 5.260 parasitos (24 Monogenea, 14 Nematoda, 10 Digenea, 2 Acanthocephala e 6 Crustacea) foram identificados. Houve um padrão de dispersão agregado de parasitos. Houve predominância de espécies de endohelmintos que apresentaram padrão semelhante quanto ao nível de comunidades componentes, ou seja, baixo número de espécies, baixa diversidade e dominância de uma única espécie, principalmente os digenéticos e nematoides em estágio larval. Cinco espécies de parasitos apresentaram correlação com o tamanho corporal dos hospedeiros. Na comunidade de peixes, a presença de endoparasitos em fase larval e adulta sugere que esses são hospedeiros intermediários, paratênicos e definitivos, refletindo seus hábitos alimentares detritívoros ou onívoros. O nível trófico e dieta influenciaram na estruturação das comunidades e infracomunidades de endohelmintos. Por fim, 38% das espécies de parasitos metazoários foram novos registros para os hospedeiros examinados.