Digestive Tract Of Fish Research Articles

Effect of Lactobacillus casei FNCC 0090 to improve gastrointestinal bacterial abundance, immune system and water quality in catfish farming

Abstract. ‘Aini N, Bachruddin M, Fatimah, Andriyono S, Wahyuningsih SPA. 2024. Effect of Lactobacillus casei FNCC 0090 to improve gastrointestinal bacterial abundance, immune system and water quality in catfish farming. Biodiversitas 25: 2130-2138. Catfish is the most widely cultivated type of fish. However, along with the increase in catfish production as an effort to fulfill the fishery stock, there is an obstacle to the emergence of disease infection caused by Aeromonas hydrophila. For this reason, good fisheries management is required. One of the efforts to deal with this is by giving probiotics Lactobacillus casei FNCC 00990. Lactobacillus casei FNCC 0090 is expected to improve the immune system of catfish through improving the blood profile of fish and increasing the number of lactic acid bacteria in the gastrointestinal tract of catfish. This research aims to determine the effect of administering the probiotic L. casei FNCC 0090 on the abundance of microbes in the fish digestive tract, immune system, and water quality in cultivating catfish infected with A. hydrophila. The research design was a completely randomized design with five treatments and five replications. The treatments were A (administering 5% probiotics and infected with 0.1 mL x 108 CFU/mL), B (10% probiotics and infected), C (15% probiotics and infected), KP (positive control with 0% probiotics and infected with pathogens), KN (negative control, without probiotics and pathogen infection). Fish are kept for 42 days; on the 35th day, the fish were infected with A. hydrophila by intramuscular injection. Probiotics were mixed with feed with a total of 108 CFU/mL. Data in the form of BAL counts and total bacterial counts of fish digestive tracts, blood profiles, and water quality were analyzed using Statistical Package for the Social Sciences (SPSS) software version 23.0 (IBM SPSS Statistics). The results showed

Organic acids mitigate Streptococcus agalactiae virulence in Tilapia fish gut primary cells and in a gut infection model

BackgroundStreptococcus agalactiae, a Gram-positive bacterium, has emerged as an important pathogen for the aquaculture industry worldwide, due to its increased induced mortality rates in cultured fish. Developing interventions to cure or prevent infections based on natural alternatives to antibiotics has become a priority, however, given the absence of scientific evidence regarding their mode of action progress has been slow.MethodsIn this study we aimed to investigate the effect of a mixture of organic acids (natural antimicrobials), AuraAqua (Aq), on the virulence of S. agalactiae using Tilapia gut primary epithelial cells and an in vitro Tilapia gut culture model. Our results show that Aq was able to reduce significantly, in vitro, the S. agalactiae levels of infection in Tilapia gut primary epithelial cells (TGP) when the MIC concentration of 0.125% was tested.Results and discussionAt bacterial level, Aq was able to downregulate bacterial capsule polysaccharide (CPS) gene expression, capC, resulting in a significant decrease in bacterial surface capsule production. The decrease in CPS production was also associated with a reduction in the pro-inflammatory IFNγ, IL1β, TNFα, SOD and CAT gene expression and H2O2 production in the presence of 0.125% Aq (P < 0.0001). The antimicrobial mixture also reduced the levels of S. agalactiae infection in an in vitro gut culture model and significantly reduced the IFNγ, IL1β, TNFα, SOD, CAT gene expression and H2O2 production in infected tissue. Moreover, genes involved in Tilapia resistance to S. agalactiae induced disease, MCP-8 and Duo-1, were also downregulated by Aq, as a consequence of reduced bacterial levels of infection.ConclusionConclusively, our study shows that mixtures of organic acids can be considered as potential alternative treatments to antibiotics and prevent S. agalactiae infection and inflammation in the Tilapia fish digestive tract.

Microplastic contamination in water, sediment, and fish from the Kahayan River, Indonesia

ABSTRACT Microplastic occurrence in the aquatic ecosystem has become of great concern worldwide because of its persistence, durability, and toxicity. Microplastics are found ubiquitous in freshwater environments, including rivers. Thus, our study assesses microplastic pollution in water, sediment, and fish of the Kahayan River, Indonesia. We first evaluated microplastics’ occurrence, abundance, and characteristics in Central Kalimantan, Indonesia. The average abundance of microplastic in water was 2.92 ± 2.62 items/L, while in sediment was 6.93 ± 3.15 items/Kg dry weight. We found 53 out of 90 fish (58.89%) had microplastics in their digestive tracts with an average abundance of 2.03 ± 3.416 items/Ind. The predominant characteristics in water were fragment and fibre and size of 150-<300 µm. Microplastics present in the sediment and the digestive tract of fish have similar dominant fibre. In terms of size, sediments and fish were dominated by 150-<300 µm, 1000–5000 µm, and 500-<1000 µm respectively with different order of proportions. The infrared spectroscopic analysis confirmed the most common polymer type to be polyvinyl chloride in water and sediment, while polyethylene was predominant in fish. Our study provides the current status of microplastic contamination for further evaluation and management of the Kahayan River, Indonesia.

Linking anatomical and histological traits of the digestive tract to resource consumption and assimilation of omnivorous tetra fishes.

This study explores the interplay between digestive tract traits, food intake, and assimilation in omnivorous tetra fishes (Psalidodon bifasciatus, P. aff. gymnodontus, and Bryconamericus ikaa) from the Iguaçu River basin, an ecologically significant region known for high endemism. We hypothesize that variations in digestive tracts across species would be associated with differences in diet, isotopic composition in fish tissues, and overall diet assimilation. To test this, we employed stereoscopic and light microscopy to characterize the gross anatomy, histomorphology, and histochemistry of fish digestive tracts. Additionally, we used stomach content and stable isotope analyses to trace fish diets. While these tetra fishes shared histological structures, disparities were noted in anatomical digestive traits and diet preferences. The smallest species, B. ikaa, with a shorter intestine, had fewer pyloric caeca and primarily consumed animal-based diets. Conversely, P. bifasciatus and P. aff. gymnodontus, with longer intestines, displayed numerous pyloric caeca and consumed a balanced mix of animal and plant items. Despite anatomical and dietary differences, all three species predominantly assimilated animal-origin food. The tetra fishes had histological variations among digestive tract segments, with the esophagus having the thickest muscular layer, gradually thinning towards the posterior intestine. The final portion of the intestine exhibited a significant expansion in the lumen perimeter, while the esophagus had the smallest lumen area. Goblet cells were most concentrated in the posterior intestine for all species. The gross anatomy of these tetra fishes aligns with their omnivorous habit, while diet assimilation was dominated by animal-origin food. These findings provide crucial insights into the structural and tissue characteristics of their digestive systems, laying the groundwork for deeper exploration into the physiological aspects of their digestive tracts and enhancing our understanding of their feeding strategies.

Accumulation, tissue distribution, health hazard of microplastics in a commercially important cat fish, Silonia silondia from a tropical large-scale estuary

The current knowledge regarding the presence of microplastics (MPs) in the digestive tracts of fish, particularly the non-edible parts, provides limited assistance in assessing the risk to human health and establishing guideline values for policy-making purposes. Therefore, we conducted the first investigation into MPs within the commercially significant catfish species S. silondia, form a major tropical estuary assessing their accumulation, characteristics, and associated risks in various tissues, particularly the consumable muscle. A sum of 132 MPs were identified, and the mean abundance of MPs were 7.40 ± 4.12 item/DT, 3.20 ± 1.69 item/gill and 2.60 ± 1.65 item/muscle found in digestive tract (DT), gill and muscle of the fish, respectively. The strong relationships of MPs among three different tissues (y = 0.6069x - 22.69, R2 = 0.7589) indicated the pathways and how MPs were influenced by the physiology of organisms. The prevalence of MPs in fish muscle demonstrated their trophic transmission to humans. Moreover, fishes with higher weight had higher MPs in their gill, and DT. The dominant type, color and size of MPs were fibrous (89.67%), violet (41%) and &amp;lt; 0.5 mm sized (94%), respectively. The high percentage of fibers suggests that they might have come from ropes, fishing nets or sewage. FTIR chemical composition analyses of microplastics (MPs) identified three primary polymer types: PET (44.5%), PE (33.3%), and PP (22.2%) in fish. These polymers are commonly associated with packaging materials, household wastes and plastic pipes. Contamination level assessment by CF (CF = 2.76) and PLI (PLI &amp;gt; 1) indicated moderately to highly contaminated fish with MPs ingestion. While the complete understanding of the direct negative effects of microplastics (MPs) on human health remains elusive, their presence in estuarine fish raises concerns for both human and ecosystem health. The findings will be useful for assessing the hazards to human health from exposure to MPs and for creating effective risk management plans to reduce those risks.

Microparticles in Wild and Caged Biota, Sediments, and Water Relative to Large Municipal Wastewater Treatment Plant Discharges.

Anthropogenically modified microparticles including microplastics are present in municipal wastewater treatment plant (WWTP) effluents; however, it is unclear whether biotic exposures are elevated downstream of these outfalls. In the fall of 2019, the present study examined whether microparticle levels in resident fish, environmental samples, and caged organisms were elevated near the Waterloo and Kitchener WWTP outfalls along the Grand River, Ontario, Canada. Wild rainbow darters (Etheostoma caeruleum) were collected from a total of 10 sites upstream and downstream of both WWTPs, along with surface water and sediment samples to assess spatial patterns over an approximately 70-km river stretch. Amphipods (Hyalella azteca), fluted-shell mussels (Lasmigona costata), and rainbow trout (Oncorhynchus mykiss) were also caged upstream and downstream of one WWTP for 14 or 28 days. Whole amphipods, fish digestive tracts, and mussel tissues (hemolymph, digestive glands, gills) were digested with potassium hydroxide, whereas environmental samples were processed using filtration and density separation. Visual identification, measurement, and chemical confirmation (subset only) of microparticles were completed. Elevated abiotic microparticles were found at several upstream reference sites as well as at one or both wastewater-impacted sites. Microparticles in amphipods, all mussel tissues, and wild fish did not show patterns indicative of increased exposures downstream of effluent discharges. In contrast, elevated microparticle counts were found in trout caged directly downstream of the outfall. Across all samples, cellulose fibers (mainly blue and clear colors) were the most common. Overall, results suggest little influence of WWTP effluents on microparticles in biota but rather a ubiquitous presence across most sites that indicates the importance of other point and nonpoint sources to this system. Environ Toxicol Chem 2024;43:1047-1061. © 2024 His Majesty the King in Right of Canada and The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

Isolation and Characterization of Soil Probiotic Bacteria in Cauvery River Basin and their Application in Aquaculture

Research on probiotics for aquatic animals is growing along with the demand for environmentally friendly aquaculture. Probiotics have been defined as live microbial supplements that improve the health of humans and terrestrial animals [1]. The micro biota in the digestive tract of fish and crustaceans is particularly dependent on the external environment due to the flow of water through the digestive tract. The need to increase disease resistance, growth of aquatic organisms and feed efficiency has led to the use of probiotics in aquaculture. In recent years, the use of probiotics in aquaculture has begun to increase [2]. There is documented evidence that probiotics can improve nutrient digestibility, increase stress tolerance and promote reproduction. Unlike previous publications, this study focuses on the role of soil probiotic bacteria isolated from the Cauvery basin in Tiruchirapalli district. Isolated microorganisms - Nitrosococcus and Neisseria were tested for their special role in aquaculture, mainly in tilapia fish (Oreochromis sp.). This study also improves the bioremediation capacity of the isolated soil bacteria, which was demonstrated by testing the water quality parameters of the probiotic used. water environment Fish growth and mortality were also measured. It was clearly observed that the use of an isolated soil probiotic from a cave river basin promoted the longevity of tilapia fish. Thus, the cultivation and use of soil probiotic bacteria in aquaculture is a promising approach in modern science.

Identification of microplastic polymers found in the digestive tract of fish from Lake Amatitlán, Guatemala

Identification of microplastic polymers found in the digestive tract of fish from Lake Amatitlán, Guatemala

Characterization of microplastics in digestive tract of commercial fish species from the Oman Sea

Microplastics (MPs) content of the digestive tract of two commercial fish from the northern shores of the Oman Sea were investigated. The MPs were characterized by optical microscopy, fluorescent microscopy, and SEM-EDX for their number, shape, size, and color. Polymer composition was analyzes using micro-Raman spectroscopy (RMS). MPs were recovered in all fish samples (100 %), with an average of 43.16 ± 8.23 items/individual in Otolithes ruber, and 29.9 ± 2.73 items/individual in Acanthopagrus latus. The predominant shape of MPs in both fishes was fiber (46 %) with black, transparent, and white colors. The majority of MPs were <1000 μm (75 %), and half of the MPs were smaller than 300 μm in size. Their synthetic nature was confirmed by Nile Red staining and determination of the elemental composition of selected items. Polypropylene (PP) and polyethylene (PE) were the dominant plastic polymers in the fish digestive tracts. This study reveals abundance distribution of MPs in digestive tract of commercial marine fish. High number of ingested MPs can alarm the accumulation of MPs in the northern of Oman Sea ecosystem with anthropogenic activities and raises issues in public health.

260 Identification of Candidate Gut Bacterial Species from Atlantic Salmon (Salmo salar) That Can Metabolize Ingredients Derived from Bioprocessed Soybean Meal

Abstract In the aquaculture industry, plant-based protein sources have emerged as an economically and environmentally sustainable replacement for traditional animal protein sources. Yet, due to decreased digestibility, the presence of anti-nutritional factors, and an increased risk of inflammation of the digestive system, the inclusions of plant-based protein ingredients must be limited in the diets of carnivorous fishes. To gain further insight on the adaptation of the fish digestive tract to plant-based protein ingredients, slurry from cultured Atlantic Salmon (Salmo salar) was used as a proxy in an in vitro model system to identify candidate gut bacterial species from fish that can metabolize bioprocessed soybean meal. Triplicate slurry cultures were supplemented with one of each of the following ingredients: fishmeal (FM – control#1), soybean meal (SBM-control#2), MEPro (bioprocessed soybean meal product), as well as three ingredients derived from bioprocessed soybean meal (SPC1 - soy protein isolate #1; SPC2 - soy protein isolate #2; SPC3 - soy protein isolate #3). Data were generated by Illumina MiSeq 2X300 sequencing of PCR-generated amplicons targeting the V1-V3 regions of the 16S rRNA gene. A comparative analysis of the most highly represented Operational Taxonomic Units (OTU) using the non-parametric Kruskal-Wallis sum-rank test and Wilcoxon pairwise test identified candidate bacterial species that were enriched in cultures supplemented with specific bioprocessed soybean meal-derived ingredients compared with non-supplemented cultures (negative control). These results indicate that certain species may utilize these ingredients. Notably, OTUs Ss_1-37437 and Ss_1-13316 were found in the greatest abundance in cultures supplemented with SPC1 (31.4 - 49.7%) and SPC2 (7.2 - 17.4%), respectively. Interestingly, both OTUs were likely to represent novel bacterial species, based on their limited nucleotide sequence identity to their corresponding valid relative: Ss_1-37437: Prevotella paludivivens (96.58%); Ss_1-13316: Acetoanaerobium sticklandii (86.51%). In contrast, the most abundant OTUs enriched in SBM- and MePro-supplemented cultures were likely strains of known bacterial species. Indeed, OTU Ss_1-00386 was most abundant in SBM-supplemented cultures (16.4 - 32.5%), and it was found to be closely related to Leuconostoc mesenteroides (98.69%), a bacterial species with reported probiotic properties, while OTU SS_1-10030, a close relative of Bacteroides graminisolvens (99.24%), was most highly represented in MePro-supplemented cultures (21.9 - 32.7%). Together, these results suggest that ingredients derived from bioprocessed soybean meal have the potential to be developed as prebiotics to modulate the gut microbiome of aquaculture fish species.

Microplastics in commercial fish digestive tracts from freshwater habitats in Northern Thailand

Microplastics (MPs) contamination in fish species was one of the emerging environmental issues as a result of the widespread presence of plastic pollution in the environment. The presence of MPs in Thailand's freshwater was scant, and in contrast to other countries, little was known about the presence of this contaminant in freshwater fish. Hence, the purpose of this study was to examine the abundance, characteristics, and variation of MPs in various Thai commercial freshwater fish species. In order to compare the differences in MP ingestion rates across different feeding zones, 166 fish representing 24 species from various feeding zones were collected. MPs were found in the gastrointestinal tracts (GIT) of all fish samples tested, which was a substantially larger number than previously reported in other locations. Of all the fish species, Anabas testudineus, Labeo rohita, and Oreochromis mossambicus had the highest concentration of MPs (34.90 ± 21.43, 34.50 ± 7.78, 34.10 ± 11.15 items/individuals). Microscopical examinations showed that the majority of MPs were fiber-shaped and blue in color. Fourier transform infrared analysis (FTIR) showed that the polymers found in fish GIT were polyethylene, polypropylene, polyethylene terephthalate, polyvinyl acetate, poly (methyl vinyl ether), poly (methyl vinyl ether), polybutadiene, poly (ethylene-co-propylene), poly (ethylene glycol) tetrahydrofurfuryl ether, poly (methyl phenyl siloxane), poly (styrene-co-divinylbenzene), and polyvinylidene fluoride. The results of this study demonstrate that demersal fish had a higher concentration of MPs than benthopelagic and pelagic fish, indicating that plastic ingestion in fish may be related to the feeding habitat. However, it was not discovered that differences in the fish's body weight and length affected the MPs' ingestion. Our findings will help people in Thailand understand which freshwater fish and fish from which feeding zones are more contaminated with MPs for human consumption.

An Overview of Microplastics in the Marine Ecosystem of North Maluku

North Maluku has been the site of microplastic study for some years. The goal of this paper is to revisit the earlier analysis. The intent is to be a quick guide for scholars studying microplastics in North Maluku. Additionally, this article's goal is to quantitatively analyse some of the findings from the research that has been done. The terms "Microplastics in the North Maluku Sea" were entered into the search engines Google Scholar and Science Direct to conduct journal and research searches. Previous studies on microplastics on Mare Island looked at sediments in the island's waters and the levels of microplastics in various kinds of sea cucumbers. A total of 272 microplastic fragments were discovered in sea cucumbers. At the same time, two stations were doing a study on deposits. Microplastics weighing between 17,000 and 37,000 particles/kg of dry sediment were discovered at the first station in Maregam. 13,839-30,666 particles/kg of silt were discovered in Marekofo. According to research conducted on the island of Ternate, skipjack tuna contains up to 948 microplastic particles that were collected from 16 market fish samples. According to studies on other fish species like Epinephelus Fuscogutattus, E. coioides, and E. Suillus, the digestive tract of fish contains 594 microplastic particles.

The effectiveness of ichthyochoric dispersal in forested wetlands of the Amazon depends on the species of fish and its size

The interaction between fish and plants in Amazon floodplain is fundamental for the maintenance of frugivorous fish and tree communities. The viability of seeds after passing through the digestive tract of fish is a central factor for seed dispersal since it can influence colonization and regeneration of these environments. Our study investigated the seed dispersal by frugivorous fish in a flooded forest in the Central Amazon. We also evaluated the seed germination speed after passage of the digestive tract of fish and how the size of fish and the seeds can influence the dispersion of tree seeds in floodplains. A total of 5,012 seeds from 49 plant species were found in the digestive tracts of 11 frugivorous fish species. The length and weight of the frugivorous fish were positively related to the size of seeds in the digestive tract. The germination of the seeds removed from the fish varied between species. The passage of the seeds of the different plant species through the digestive tracts of the fish did not significantly increase the germination speed. Considering the anthropogenic pressures present in these environments, we can expect that a reduction in body size for some species of fish, due to overexploitation, may have negative consequences for some tree species that are dispersed mainly via ichthyochory.

Isolation and identification of proteolytic lactic acid bacteria from freshwater pomfret (Colossoma macropomum) intestine

The production of freshwater pomfret (Colossoma macropomum) in Indonesia is abundant, but the digestive tract waste weighing 10-15% of the fish body is not widely utilized. The fish's digestive tract can potentially produce lactic acid bacteria (LAB). Lactic acid bacteria have a proteolytic system that can produce extracellular protease enzymes. Protease enzymes are the most widely utilized enzymes in various industries and have a global revenue of up to $2.1 billion in 2021. Protease enzymes derived from microbes are in great demand due to the efficiency of time, place, cost, and better cultivation techniques than animal and plant sources. This study aimed to isolate and identify proteolytic lactic acid bacteria from the intestines of freshwater pomfret fish and determine their proteolytic index. The methods used were morphological, biochemical, sugar, and proteolytic tests. The BAT-A isolate with the highest proteolytic index of 2.52 with characteristics of Gram-positive, non-spore, facultatively anaerobic, catalase-negative, non-motile, homofermentative, can ferment glucose, maltose, lactose and sucrose which were then identified as proteolytic lactic acid bacteria Enterococcus sp which has the potential as a candidate source of protease enzymes from bacteria isolated from the intestines of freshwater pomfret.

KELIMPAHAN BAKTERI SALURAN PENCERNAAN IKAN NILEM (Osteochilus vittatus) YANG DIBERI PAKAN DENGAN SUPLEMENTASI GARAM (NaCl)

Bonylip barb fish is an aquaculture commodity that has the potential to be developed in Banyumas district. In its cultivation activities, bonylip barb are able to consume artificial feed well. The feed consumed will affect the digestive condition. The fish digestive tract is a complex system whose main functions are digestion and absorption. Nutrient absorption in intestinal cells is influenced by active transport of Na+ (sodium) ions. Na+ and Cl ion levels are obtained through water and feed. This study aims to determine the effect of salt supplementation in commercial feed with different concentrations on bacterial abundance. The research was carried out experimentally with salt supplementation doses (0%, 1%, 2%, 3%, and 4%; w/w) to be applied to bonylip barb seeds (5-7 cm) for 60 days. Research parameters include bacterial abundance, positive and negative gram tests. The results showed that the treatment with the addition of 2% NaCl gave a total number of bacteria that tended to be higher than the control (0% NaCl). The total number of bacteria in the digestive tract of Nilem fish that were given NaCl addition to the feed ranged from 3.78 ± 6.27 x 106 CFU/gram to 32.04 ± 19.51 x 106 CFU/gram. The addition of NaCl affects the proportion of gram positive and negative in the digestive tract of tilapia (Oreochromis niloticus). Gram positive bacteria tended to dominate in the 2% NaCl treatment at 69.99% and gram negative bacteria at 21.69%.

Microplastics contamination in commercial fish landed at Lengkong Fish Auction Point, Central Java, Indonesia

Plastic is one of the main pollutant sources that are difficult to decompose and then carried into the ocean and fragmented into smaller parts (microplastics) due to UV radiation and water currents. Their small size means that microplastics are often ingested by aquatic organisms, such as fish. This research aimed to determine the presence, abundance, and types of microplastics in the digestive tract of four dominant fishes landed at Lengkong Fish Auction Point, Cilacap, Central Java, i.e. threadfin ( Eleutheronema tetradactylum), mackerel ( Rastrelliger sp.), threadfin bream ( Nemipterus japonicus), and hairtail ( Trichiurus lepturus). We found microplastics in the digestive tract of four selected fishes with a frequency of occurrence of 100%. The concentration of microplastics in fish digestive tracts is relatively high, with a value range of 12 ±2.86 to 28.33 ±8.11 particles∙ind.-1. Microplastics were found in films, fibres, fragments, and granule shape types with various colours: brown, purple, blue, black, green, transparent, and yellow. The polymers found were polystyrene (PS), nylon, acrylonitrile butadiene styrene (ABS), polyurethane (PU), polypropylene (PP), high-density polyethylene (HDPE), and low-density polyethylene (LDPE). The present study provides baseline data for microplastics contamination in commercial fish species landed at Lengkong Fish Auction Point, Cilacap, Central Java, Indonesia. The fact that we discovered PU, the most harmful polymer, piques our attention.

Comparative Morphology of the Digestive Tract of African Bush Fish (Ctenopoma acutirostre) and Paradise Fish (Macropodus opercularis) Inhabiting Asian and African Freshwaters.

Anabantidae is a large and diverse group of fish cultured both under aquaculture conditions and as a hobby. These fish share a common structural feature in the form of an additional respiratory organ. Despite the enormous availability of these fish worldwide, little is known about their feeding preferences in husbandry and their influence on homeostasis under both industrial and domestic conditions. This study describes, for the first time, the structure of the digestive tracts of two Anabantoidei fishes: African bush fish (Ctenopoma acutirostre) and paradise fish (Macropodus opercularis). The overall structure of the digestive tract and its histological structure were analyzed and compared in both fish species. Physiological predispositions indicated a predominance of omnivorous fish traits in M. opercularis in contrast to C. acutirostre, which has several morphological traits indicating greater adaptation to carnivory, particularly ichthyophagy. The results obtained will allow further research to be conducted in the future to optimize the nutrition and feeding of these fish and to develop appropriate dietary recommendations.

ANALYSIS OF BACTERIAL ABUNDANCE IN THE INTESTINES OF COMMON CARP Cyprinus carpio TREATED WITH THE PROBIOTIC Bacillus subtilis

Efforts to increase microbial populations in fish intestines tract can be done by utilizing microbes in the fish's digestive tract as probiotics. The application of Bacillus subtilis in fish feed mixtures can provide better growth performance in modifying microbes in the intestines of fish. The aim of this research was to analyze the bacterial community in the intestines of Common Carp(Cyprinus carpio) that have been given probiotics from the bacteria Bacillus subtilis with metagenome sequencing using 16S rRNA through Next Generation Sequencing (NGS) technology. Common carp samples were collected from maintenance conducted with different treatments, namely control fish without probiotic administration and fish treatment with mixed feed probiotic Bacillus subtilis. This research was conducted in the Laboratory of Fisheries Biotechnology, Faculty of Fisheries and Marine Science, Padjajaran University. Then molecular identification was carried out using Illumina's NGS in Novogene, Singapore. The results of the identification of using probiotic bacteria Bacillus subtilis in Common carp(Cyprinus carpio) feed affect the bacterial community in the fish intestine. In the intestines of carp that were given probiotics, the highest abundance was Proteobacteria, Fusobacteriota, and firmicutes.The highest abundance at the genus level in both samples was domiciled by the genus Cetobacterium followed by the Sphingomonas and Aeromonas.

Digital phenotyping of individual feed intake in Atlantic salmon (Salmo salar) with the X-ray method and image analysis

The primary barrier to research into feed efficiency of Atlantic salmon (Salmo salar) is the lack of a reliable method to assess individual feed intake in large cohorts of fish over a growth period. A method with potential is the X-ray method, which images radio-opaque markers (beads) in feed consumed by fish. However, the time taken to count the markers in the digestive tract of fish is extremely onerous and the method has previously been shown to have low repeatability. Furthermore, the method has not been assessed and optimized for Atlantic salmon. Firstly, we made use of image analysis to count beads within the digital radiographs, which was highly correlated to manual counting by human observers (R2 = 0.99). Remarkably, image counting was up to 6 times faster than human counting when the number of beads per fish was high (&amp;gt; 300 per fish). We investigated the potential effect of different sources of error on the feed mass to bead count calibration equation and found the effects of X-ray exposure setting and the position of pellets on the X-ray plate to be negligible on the bead counts of both human and image analysis. We tested different feeding periods with the time of the X-ray images to minimize the loss of beads through defecation. We found that fish should be X-rayed within 6.5–11 hours of first being offered feed for a 6-hour feeding period which fed the entire daily ration. Lastly, we assessed the repeatability of feed intake over a 70-day growth period from 80–300 grams and found feed intake to be significantly and moderately repeatable (r = 0.45 ± 0.11), indicating developments in the method result in a consistent ranking of individual fish based on feed intake from three repeated measurements. The X-ray method combined with image analysis greatly reduces counting time without compromising accuracy, achieves promising repeatability, and is feasible in Atlantic salmon parr.

Влияние пробиотика, иммобилизованного на энтеросорбенте, на интенсивность роста и физиологические показатели красной тиляпии (Oreochromis mossambicus × Oreochromis niloticus)

The article considers a method to obtain environmentally friendly aquaculture products (red tilapia (Oreochromis mossambicus × Oreochromis niloticus) by adding the probiotic preparation Ecoflor to the balanced mixed feed. The probiotic component of the preparation formed by several strains of bifid and lacto bacteria gives the prepa-ration ability to improve the intestinal microflora of fish, activate the immune system, remove unfavorable microflora formed by metabolic products, heavy metals, radionuclides, toxins and metabolites, increase the rate of formation and accumulation of biomass of beneficial microflora in the digestive tract of fish. In the Aquaculture Technical Center under Astrakhan State Technical University there were grown 4 groups of red tilapia, 15 species in each group. Three experimental groups were fed with compound feed with the addition of probiotic Ecoflor by 2, 4 and 6 g/kg. The results were compared between the experimental groups, as well as with the control. It has been proved that feeding red tilapia with balanced mixed fodders with the addition of the immobilized probiotic preparation “Ecoflor” at a dose of 4 g/kg of feed helps to activate the protective functions of the body, normalize the metabolic processes, optimize digestive processes. The absolute increase in the group that received food with a probiotic at a dose of 4 g/kg of feed was 7.7 more than in the control. It significantly exceeded the increase in other experimental groups, which allows reducing feed costs to 1.1 units. The use of the developed compound feed in the cultivation of red tilapia makes it possible to obtain eco-friendly fish bio-products even if the waters used for fish breeding are polluted.