Feeding Habits Of Fish Research Articles

An Investigation on the Food and Feeding Habit of <i>Sarotherodon Galilaeus </i>(Cichlidae) in Egbe Reservoir, Ekiti State, Nigeria

A study on the food and feeding ecology of <i>Sarotherodon galilaeus</i>, a species of cichlid found in Nigeria's Egbe Reservoir. For the investigation, 305 fish specimens were used. The stomach contents were analyzed using diet indices such as stomach fullness, numerical approach, and frequency of occurrence method. Additionally, the Geometric Index of value (GII) was used to determine the relative value of these food products. The findings showed that both adult and juvenile <i>Sarotherodon galilaeus</i> fed on nine various food sources. The variety of food items included rotifers, algae, desmids, diatoms, protozoa, detritus, aquatic insects, aquatic plants, and insect larvae. The inclusion of detritus in the food items suggests that the fish species graze on both surface water and bottom sediments. Algae had the highest frequency of occurrence (46.39%) in both sizes and seasons, whereas rotifer had the lowest value (1.55%). Since it is possible to create the artificial diet required for this species' mass production in Nigeria, the findings of this study are very significant for the culture of that species<i>. Sarotherodon galilaeus</i> can be classified as an omnivore because it consumed a variety of foods. Since feeding accounts for 60–65% of the aquaculture industry for any species being raised, research on fish diet and feeding habits is essential to developing an effective aquaculture management system. As a result, the fish species may be raised in our garden.

Pervasive Microplastic Ingestion by Commercial Fish Species from a Natural Lagoon Environment

Microplastics have emerged as a significant global environmental concern in the recent decade. The aim of this study was to elucidate microplastic contamination of commercial fish species in a natural lagoon environment. Microplastic contamination was examined in the gastrointestinal tracts and gills of 157 commercial fish from 18 species with varying feeding habits in a vital and sensitive lagoon ecosystem, which connects to the Indian ocean. Microplastics were extracted using digestion, followed by stereomicroscopic inspection using Nile Red stain, and identified via μ-FTIR analysis. Over half of studied fishes ingested microplastics (54.14%). Filaments (50%) and blue items (43%) were the most commonly ingested. Of all the fish species, Eubleekeria splendens had the highest average concentration of microplastics in GIT (1.41 ± 2.52 items/g w.w. tissues), although no statistically significant difference in amount of ingested microplastics (items/g w.w. tissues) was observed among species. The highest concentrations of inhaled microplastics were recorded in Sillago vincenti (1.38 ± 1.30 items/g w.w. tissues). The majority of the extracted microplastics (33%) belonged in the size class 500–1500 μm with rayon, polyethylene terephthalate, and polypropylene as the primary polymers. This study found no correlation between microplastic ingestion and fish species and feeding habits, but a positive correlation with fish size was observed. These findings reveal widespread microplastic contamination in edible fish, posing potential risks to commercially important species due to increasing pollution in lagoon ecosystems.

Feeding habits of the longfin goatfish Upeneus supravittatus Uiblein and Heemstra, 2010, along Chennai coast, south India

Recognising the need to understand the feeding habits of marine fishes, a study was undertaken on the longfin goatfish Upeneus supravittatus Uiblein and Heemstra, 2010, which contributed to trawl fisheries along Chennai coast (south-east coast of India). Dataon trophic attributes such as mouth gape area, gill raker counts, stomach and intestine lengths and gut condition and contents were collected and analysed to determine condition index, index of relative importance (IRI), niche breadth and trophic level (TrL) with reference to two variables, namely, body size (small, medium and large) and season (post north-east monsoon (PNE); summer (SUM); south-west monsoon (SW); north-east monsoon (NE). The mouth gape area of U. supravittatus was 129.3 mm2. The maximum body depth-total length ratio was 1:5.0; gill rakers in lower arch was 29 and the relative intestine length was 0.48. Empty stomach contributed 56.1% of the samples. U. supravittatus fed on prey belonging to 25 Orders and >40 Genera. Decapods such as shrimps and crablets were the main prey followed by fishes. The IRI of decapods was 6474 and that of fishes was only 193. The maximum prey size predated by the fish was 33.5 and 9.8% in terms of the predator’s length and weight, respectively. Higher prey diversity was noticed in small size group and during south-west monsoon season. The narrow niche breadth of 0.20 showed the selective nature of the fish to feed on decapods. The fish is a benthic carnivore with a mean trophic level of 3.58. The trophic level decreased with body size. Diet similarity was evident between north-east and post north-east monsoon and between summer and south-west monsoon seasons. Diversity indices showed marginal variation in prey diversity among size groups and among seasons. This study paves way for estimating production efficiency of U. supravittatus. Keywords: Diet composition, Index of relative importance, Trophic level, Trophic morphology, U. supravittatus

Po-210 in plankton and fish from coastal waters (gulf of Trieste, northern Adriatic Sea)

The activity concentrations of Po-210 were determined in seawater (<0.45 μm), suspended particulate matter (0.45–20 μm), fractionated plankton (20–50 μm, 50–200 μm, >200 μm) and tissues from four fish species, namely European seabass (Dicentrarchus labrax), Golden grey mullet (Chelon auratus), Gilt-head bream (Sparus aurata) and Common pandora (Pagellus erythrinus), collected in the Gulf of Trieste (northern Adriatic Sea). The activity concentration of Po-210 in seawater varied from 0.4 to 2.2 mBq/L in the dissolved phase (<0.45 μm) and from 0.4 to 0.8 Bq/L in suspended particulate matter (0.45–20 μm). Plankton fractionation showed the levels of 62–395 Bq/kg Po-210 in the >200 μm mesoplankton fraction, 65–459 Bq/kg in 50–200 μm and 52–537 Bq/kg in 20–50 μm microplankton fractions. No significant differences were found between fractions. The Po-210 distribution trend in fish tissues was in order: liver > stomach with intestine > kidney > spleen > gonads > gills > muscle. Bioaccumulation factors were determined for fish tissues indicating that the amount of Po-210 mostly depends on fish feeding habits. Hence, the main pathway entry of Po-210 is through ingested food. The highest estimated average total annual effective ingestion doses of Po-210 are obtained via the consumption of Common Pandora (7.1 μSv/year to 16.5 μSv/year) while the lowest doses are due to the consumption of European seabass (0.32 μSv/year to 0.76 μSv/year). Comparison with levels reported for other Mediterranean and Atlantic areas showed that only activitiy concentrations of Po-210 in fish appear significantly different, most likely because different fish species were analysed. The human dose exposure via fish consumption in the area is rather low.

Biogeographical diet variation within and between the rabbitfishes Siganus corallinus, Siganus doliatus, Siganus trispilos and Siganus virgatus.

Feeding habits of herbivorous fishes play an important role in shaping the form and function of coastal marine ecosystems. Rabbitfishes (Siganidae) are important consumers of macroalgae on Indo-West Pacific coral reefs. However, it is unclear how their diet varies among and within species at biogeographical scales, casting doubt on their precise functional roles across different regions. The present study assessed the inter- and intra-specific diet variation of four rabbitfishes (Siganus trispilos, Siganus corallinus, Siganus virgatus and Siganus doliatus) factored by morphological relatedness among populations from Ningaloo Reef (western Australia), the Great Barrier Reef (GBR, eastern Australia) and the Yaeyama Islands (Okinawa Prefecture, Japan). Results showed that the region had a strong effect on diet, effectively reducing the expected effect of morphologic similitude. While intra-specific differences were only significant when populations inhabited different regions; interspecific differences were not as predicted, with different morphotypes having similar diets when populations inhabited the same regions. Rabbitfishes consumed more corticated and filamentous macroalgae on the GBR, more foliose and membranous macroalgae at the Yaeyama Islands, and more leathery macroalgae at Ningaloo Reef. The findings indicate that rabbitfishes have high diet plasticity, and hence their functional role as mediators of competition between macroalgae and corals can change across biogeographic regions. Local context is therefore important when assessing the diet and functional role of herbivorous fishes. As climate change unfolds, shifts in the distribution, trophic behaviour and function of species are expected, making the study of trophic plasticity more important.

Probing into the impacts of endogenous and exogenous short chain fatty acids (SCFAs) in fish health and growth

Abstract Short-chain fatty acids (SCFAs) are small organic acids exist in the fish gastrointestinal tract, mainly acetate, propionate, and butyrate. These SCFAs are produced through anaerobic fermentation of dietary non-digestible carbohydrates by gut microbes. Though enough studies have been devoted to showcasing the potential of SCFAs in human nutrition, the research on their production, potential, and existence in fish has been comparatively limited until recently. This review aims to provide a comprehensive overview of the current knowledge regarding SCFAs in aquaculture. It starts with commenting on the different sources, such as substrate and microbial species that are responsible for the production of SCFAs and their transportation and ends up depicting the relationship between biofloc technology and SCFAs production. This review also discusses the factors influencing SCFA production, such as environment, diet, and feeding habits of fish. Furthermore, the biological functions of SCFAs have been highlighted, and critical findings were compiled, including immunomodulatory effects, physiological response, gut health, and immunity.

Dietary partitioning among three cryptobenthic reef fish mesopredators revealed by visual analysis, metabarcoding of gut content, and stable isotope analysis

AbstractUnderstanding how mesopredators partition their diet and the identity of consumed prey can assist in understanding the ecological role predators and prey play in ecosystem trophodynamics. Here, we assessed the diet of three common coral reef mesopredators; Pseudochromis flavivertex, Pseudochromis fridmani, and Pseudochromis olivaceus from the family Pseudochromidae, commonly known as dottybacks, using a combination of (i) visual stomach content analysis, (ii) stomach content DNA metabarcoding (18S, COI), and (iii) stable isotope analysis (δ15N, δ13C). In addition, P. flavivertex is found in two distinct color morphs in the Red Sea, providing an opportunity to analyze intra‐morph differences. These techniques revealed partitioning in the dietary composition and resource use among species. Arthropods comprised the main dietary component of P. flavivertex (18S &gt; 60%; COI &gt; 10%) and P. olivaceus (18S = 57.2%), while P. fridmani ingested predominantly mollusks (18S = 51.3%, COI = 24.6%). Despite being small predators, microplastics were found in the gut content of some of these fishes. Stable isotope analysis showed differences in species' isotopic niche breadth and trophic position. Pseudochromis olivaceus presented the largest isotopic niche (SEAC = 1.61‰2), while P. fridmani showed the smallest isotopic niche (SEAC = 0.45‰2) among species. Although the two techniques used for stomach content analysis did not show differences in the diet within color morphs of P. flavivertex, they differed in the isotopic niche and resource use. Despite our limited sampling, our findings provide evidence of species‐specific differences in the trophic ecology of dottybacks and demonstrate their important role as predators of cryptic invertebrates and small fishes. This study highlights the importance of combining several approaches (short‐term: visual analysis and DNA metabarcoding; and long‐term: isotope analysis) when assessing the feeding habits of coral reef fish, as they provide complementary information necessary to delimit their niches and understand the role that small mesopredators play in coral reef ecosystems.

Description of a large specimen of Paralepis elongata (Brauer, 1906) from Angola, southeastern Atlantic Ocean (Aulopiformes: Paralepididae).

The elongate barracudina, Paralepis elongata (Brauer, 1906), received limited attention in the past, with only a few individuals documented, mostly in publications focusing on the feeding habits of large predatory pelagic fishes. Furthermore, the taxonomic history of the species is complicated, with some earlier sources providing incorrect information that influenced subsequent works. As a result, the accurate distribution range of P. elongata remains uncertain. An adult male specimen of P. elongata, representing the largest known individual, is reported from off Angola, southeastern Atlantic. A detailed description is provided, and the literature records of the species are reviewed and discussed.

Microalgae as fishmeal alternatives in aquaculture: current status, existing problems, and possible solutions.

Fishmeal is an indispensable ingredient for most aquatic animals. However, the finite supply and escalating price of fishmeal seriously limit its use in aquaculture. Thus the development of new, sustainable protein ingredients has been a research focus. Microalgae are potential fishmeal alternatives owing to their high protein content and balanced amino acid profile. Studies suggest that suitable replacement of fishmeal with microalgae is beneficial for fish growth performance, but excessive replacement would induce poor growth and feed utilization. Therefore, this paper aims to review research on the maximum substitutional level of fishmeal by microalgae and propose the main issues and possible solutions for fishmeal replacement by microalgae. The maximum replacement level is affected by microalgal species, fish feeding habits, quality of fishmeal and microalgal meals, and supplemental levels of fishmeal in the control group. Microalgae could generally replace 100%, 95%, 95%, 64.1%, 25.6%, and 18.6% fishmeal protein in diets of carp, shrimp, catfish, tilapia, marine fish, and salmon and trout, respectively. The main issues with fishmeal replacement using microalgae include low production and high production cost, poor digestibility, and anti-nutritional factors. Possible solutions to these problems are recommended in this paper. Overall, microalgae are promising fishmeal alternatives in aquaculture.

Human health risks associated to trace elements and metals in commercial fish from the Brazilian Amazon

Fish constitutes the main protein source for the Amazonian population. However, the impact of different anthropogenic activities on trace element and metal accumulation in fish and their risks for human health at a regional scale remain largely unexplored. Here we assessed exposure levels of 10 trace elements and metals (Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Pb, and Hg) in 56 samples belonging to 11 different species of fish from the Brazilian Amazon. We studied the relationship between exposure levels, fish origin, and fish feeding habits, and assessed toxicological and carcinogenic risks for the Amazonian population. No significant correlation was found between sampling site and exposure levels to the studied elements, but a significant difference was found between the accumulation of some metals and the position of the fish species in the food chain. The concentrations of Cr and Hg in fish flesh were found to exceed the Brazilian limits for human consumption. This study shows that current fish consumption patterns can lead to estimated daily intakes of Hg, As and Cr that exceed the oral reference dose, thus posing a toxicological concern. Furthermore, carcinogenic risks may be expected due to the continued exposure to Cr and As. The results of this study show that the consumption of wild caught fish in the Amazon region should be controlled. Moreover, continued monitoring of trace element and metal contamination in fish and on the health of the Amazonian population is recommended, particularly for riverine and indigenous communities.

Feeding Patterns of Fish in Relation to the Trophic Status of Reservoirs: A Case Study of Rutilus rutilus (Linnaeus, 1758) in Five Fishing Waters in Serbia

The roach, Rutilus rutilus (Linnaeus, 1758), is one of the most common fish species in mesotrophic and eutrophic lakes throughout Europe. In the Serbian reservoirs selected for this study, this species accounts for the majority of juvenile fish biomass. The aim of this study was to investigate the diet composition of juvenile roach to assess their niche based on resource availability in five Serbian reservoirs with different trophic statuses. A modified Costello graph and Kohonen artificial neural network (i.e., a self-organizing map, SOM) were employed to examine the feeding habits of 142 specimens of roach caught in five reservoirs. Our results show that juvenile roach use zooplankton, benthic macroinvertebrates, algae and detritus in their diet. In addition, five neuron clusters (A, B, C, D and E) were isolated in the SOM output network. The SOM identifies specimens that share similar feeding patterns and categorizes them onto the same or adjacent neurons, determined by dominant prey. In terms of the number of specimens, cluster B was the most numerous, and the predominant prey of these specimens were Daphnia sp., Bosmina sp. and calanoid and cyclopoid copepods. The cluster with the lowest number of specimens is cluster C, and the specimens in it benefited from Chironomidae and Insecta. Due to the different trophic statuses of the reservoirs selected for this study, knowledge of fish feeding habits is essential for the formulation of effective conservation and management strategies for both the species and the reservoirs.

Fatty Acid Profile of Snakehead (Channa striata) and Its By-Product by GC-MS

The increasing demand for sustainable and high-quality food sources has led to a growing interest in exploring alternative protein options. Fish-derived products, known for their nutritional value, unique flavor profiles, and potential health benefits, have gained significant attention. Among these, snakehead (Channa striata) and its by-products have emerged as promising resources for various food applications, including fish powder production. Fish powder holds immense potential in the food industry as a versatile ingredient, capable of enhancing nutritional content while minimizing waste. This research focuses on investigating the fatty acid composition and volatile compounds present in snakehead fish powder and its by-products. The study employs a combination of analytical techniques, namely gas chromatography-mass spectrometry (GC-MS) and lipid extraction methods, to identify and quantify fatty acids and volatile compounds in the fish powder samples, providing a comprehensive chemical profile. The data reveals variations in the fatty acid composition among different components of the snakehead powder samples, influenced by the fish's feeding habits. The presence of essential fatty acids, including omega-3 and omega-6, highlights the potential health benefits of consuming snakehead powder. Moreover, the identification of odd chain saturated fatty acids (OCS-FAs) in the samples indicates their potential contribution to human health. Notably, snakehead powder contains docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which have reported preventive effects on human coronary artery disease. In conclusion, snakehead powder is a valuable source of protein and essential fatty acids, with potential implications for human health. The study emphasizes the significance of incorporating polyunsaturated fatty acids (PUFAs) into the human diet, potentially through fish powder consumption. Overall, the findings highlight the potential benefits of snakehead meat, head, skin, and bone, encouraging the development of functional food products and their potential use in preventing stunting.

Dependence of element composition of bile of freshwater and marine fishes on some abiotic and biotic factors

IntroductionThe elemental composition and physical properties of fish bile is a very important marker for ecotoxicological and physiological studies as bile is able to accumulate elements from environmental compartments. In the present study we focused on the effects of long term (seasons and years) and spatial distance (different water bodies) as well as other biotic (feeding habits, fish species, gut morphology) and abiotic (water salinity) factors on element composition of bile of 429 individuals belonging to 22 forms/species of fishes.MethodsElement composition was determined using an inductively coupled plasma optical emission spectrometry. The fishes were analyzed from one marine (the Kandalaksha Gulf of the White Sea), two freshwater oligotrophic (Teletskoye and Baunt lakes), and one freshwater eutrophic water body (Chany Lake). In parallel, we have estimated the volume and density of bile from the same fishes using an automatic pipette and electronic balance.Results and discussionBased on fish bile density and volume data, we hypothesize that gastric fish species (those fishes that have a stomach) require a low volume of bile, but with higher density if compared to agastric fish species (those lacking a stomach) that mainly possessed large volumes of bile, but with a lower density. We have found that the concentrations of the following Na, K, Ca, Mg, S, P (major elements) and Al, Cu, Fe, Sr, Zn (trace elements) were the highest among the 28 elements studied. There were significant findings to contribute to a better understanding of the physiology of bile. First, we have determined the conditions formed in a water body in a given year (season) are more important for element composition of fish bile rather than other tested factors (feeding habits, gut morphology, etc.). Second, the feeding habits of fishes (carnivorous compared to non-carnivorous) had a significant effect based on differences among several elements. Third, the clear distinction between marine and freshwater fishes was found only for K and Na. Understanding which elements are produced as part of waste elimination and those that are present as a consequence of vital biological functions could improve the ecotoxicological study of bile as a marker of heavy metal contamination.

Seasonal Changes in Zooplankton Population in Rainfed Rice-fish System

Integration of aquaculture in vast rainfed waterlogged lowlands can be an acceptable option for improvement of farm productivity and income in the country, particularly in the easter India. An adaptable technology on rice-fish, prawn, vegetable, fruits and other crops diversified farming system called Rice-fish System· has been developed at Central Rice Research Institute, Cuttack for waterlogged rainfed lowlands (Sinhababu and Venkateswarlu, 1995). Studies on the food and feeding habit of fish in this system is an important aspect for optimizing the fish productivity. Some information is available on the plankton profile of the irrigated rice field mainly (Saha and Ramakrishna, 1962; Li and Pan, 1992) and deep water ecology (Das et al., 1991) and also in shallow rainfed rice-fish seed system (Sinhababu et al., 1992), but not in the rice-fish system. We studied the seasonal changes in the zooplankton population in the system.

A comparison of digestive strategies for fishes with different feeding habits: Digestive enzyme activities, intestinal morphology, and gut microbiota.

Fish feeding habit determines the digestive tract structure and intestinal microflora. However, the relationship between feeding habit, digestive intestinal morphology, and microbial diversity of omnivorous, herbivorous, plankton feeder, and carnivorous fish from the same environment has not been compared. This study compared the digestive enzyme activities, intestinal morphology, and intestinal microflora of omnivorous (Carassius auratus), herbivorous (Ctenopharyngodon idellus), carnivorous (Siniperca chuatsi), and plankton feeder (Schizothorax grahami) fishes and predicted the potential functions of specific microflora on different nutrients. Twelve intestine samples were collected from each of the four fishes from Dianchi Lake. The composition and diversity of microbial communities were determined by using high-throughput sequencing of 16S rDNA. The results showed that the carnivorous fish (S. chuatsi) had higher trypsin and pancrelipase activities in the hepatopancreas and enteropeptidase in the intestine, but lower amylase activities in the intestine. The carnivorous fish intestine had more microvilli branches and complex structures than other fish species in the order carnivorous > herbivorous > plankton feeder > omnivorous. The intestinal microflora diversity was higher in the omnivorous fish and followed the order omnivorous > herbivorous > plankton feeder > carnivorous. Acinetobacter species and Bacteroides species were the most dominant flora in the carnivorous and herbivorous fishes, respectively. Acinetobacter species and Pseudomonas species might help the host to digest protein, while Bacteroidetes species may help the host to digest cellulose. Taken together, feeding habit determines the digestive enzyme activities, intestinal tissue morphology, and differential colonization of fish intestinal flora. The knowledge obtained is useful in feed formulation and feeding practices for the studied fish species.

Food Habits of Snakehead, Channa Striata (Bloch), in Aquatic Habitats: a Review Literature

Snakehead fish as a fish of high economic value is currently still caught through nature where cork maintenance has not been widely done. Snakehead fish contains high protein, good for health can also for recover damaged. This investigation intends to produce findings from earlier research into the feeding patterns of snakehead fish (Channa striata) in aquatic environments. Because it can serve as a resource for the public and other parties in terms of ecological and biological studies as well as serve as a guide for activities involving the farming of snakehead fish, this study literature is fascinating to address the feeding habits of snakehead fish (Channa striata). Fish fries are the principal diet for carnivorous snakehead fish. when zooplankton or other tiny crustaceans are more commonly consumed by snakehead fish larvae. This disparity in eating patterns is determined by things including fish kind, age, food availability, environment, and fish size. Due to the lack of food, the effects of the season, and the time spent searching for food, snakehead fish are found to have an empty stomach in both their larval and adult stages.

Effects of microplastics, pesticides and nano-materials on fish health, oxidative stress and antioxidant defense mechanism.

Microplastics and pesticides are emerging contaminants in the marine biota, which cause many harmful effects on aquatic organisms, especially on fish. Fish is a staple and affordable food source, rich in animal protein, along with various vitamins, essential amino acids, and minerals. Exposure of fish to microplastics, pesticides, and various nanoparticles generates ROS and induces oxidative stress, inflammation, immunotoxicity, genotoxicity, and DNA damage and alters gut microbiota, thus reducing the growth and quality of fish. Changes in fish behavioral patterns, swimming, and feeding habits were also observed under exposures to the above contaminants. These contaminants also affect the Nrf-2, JNK, ERK, NF-κB, and MAPK signaling pathways. And Nrf2-KEAP1 signalling modulates redox status marinating enzymes in fish. Effects of pesticides, microplastics, and nanoparticles found to modulate many antioxidant enzymes, including superoxide dismutase, catalase, and glutathione system. So, to protect fish health from stress, the contribution of nano-technology or nano-formulations was researched. A decrease in fish nutritional quality and population significantly impacts on the human diet, influencing traditions and economics worldwide. On the other hand, traces of microplastics and pesticides in the habitat water can enter humans by consuming contaminated fish which may result in serious health hazards. This review summarizes the oxidative stress caused due to microplastics, pesticides and nano-particle contamination or exposure in fish habitat water and their impact on human health. As a rescue mechanism, the use of nano-technology in the management of fish health and disease was discussed.

Effects and regulatory pathway of proopinmelanocortin on feeding habit domestication in mandarin fish

Proopiomelanocortin (POMC) is a hormone precursor, and has been reported to participate in domestication. However, its effects on feeding habit domestication in fish are poorly understood. Mandarin fish (Siniperca chuatsi) feeds solely on live prey fish since first-feeding. In the present study, the high expression of pomc in mandarin fish, both the pomc siRNA and MC4R inhibitor treatments increased the success rate of domestication from live prey fish to dead prey fish and food intake of dead prey fish, suggesting the role of pomc on the special feeding habit of live prey fish in mandarin fish. In addition, one c-fos binding site was identified in the region that from −1053 bp to −931 bp upstream of the transcription start site of pomc, and this region exhibited positive promoter activity. The mandarin fish brain cells treated with c-fos siRNA displayed suppressed pomc mRNA expression, indicating that c-fos positively regulated pomc expression. Furthermore, the mRNA expression of c-fos was higher in the mandarin fish which were more difficult to domesticate. The results of ChIP assay and inhibitor treatment confirmed that the activation of c-fos gene by histone H3K4me3 was catalyzed by Setd1b in mandarin fish. Three open peaks were found at the upstream regulatory region of setd1b by ATAC-seq, and the mRNA expression of setd1b was higher in the mandarin fish which were more difficult to domesticate. These results indicated that Setd1b could methylate histone H3K4 to activate the c-fos transcription, maintaining the high expression of pomc, which might contribute to the special feeding habit of mandarin fish.

An Evaluation on Fish Diet Composition Studies in Türkiye

Determination of the dietary composition and feeding habits of fish is important to explore and compare trophic interactions, food web structure, population, and ecological dynamics within and between aquatic ecosystems and to ensure sustainability. Factors such as global warming in the world and the effects of human activity cause the reduction of fish populations to the deterioration of the ecological balance. That is why we need to fill scientific knowledge gaps to discover and protect biodiversity. In this study, studies that determine the dietary composition of fish species distributed in our country's waters were brought together and the methods used were examined. When we examine these studies; It has been observed that information on the diet compositions of threatened and important commercial fish species is lacking, and existing studies are concentrated in certain areas. It has been determined that the studies carried out in the Black Sea and Aegean Seas are more than in the Mediterranean and Marmara Seas, there are no studies in the Southeastern Anatolia region, and there are few studies in the inland waters of the Mediterranean, Marmara, and Aegean regions.

Food and feeding habits of the large cyprinid fishes in the upper Blue Nile River, Ethiopia

Food and feeding habits of large cyprinid fishes (Labeobarbus intermedius, Labeobarbus nedgia, and Labeo forskalii) had been investigated in the upper Blue Nile River, Ethiopia. Four sampling sites were selected and specimens were sampled during the post-rainy (November 2016) and dry (March 2017) seasons by gillnets of 6 cm, 8 cm, 10 cm, 12 cm, and 14 cm mesh sizes. Totally 401 fishes were collected and about 30.4% (122) of the samples were documented with empty guts and 279 (69.6%) of them were with non-empty guts. The whole contents of all non-empty gut specimens were taken, labeled, and preserved using a 5% formaldehyde solution for further analysis. In the laboratory, gut contents were examined and identified using compound and stereo microscopes. The relative importance of different food items in the diet compositions was analyzed using a frequency of occurrence and volumetric analysis. During the post-rainy season, insects and phytoplankton were mostly ingested as food items. However, during the dry season, phytoplankton was the most important food item in the diet of all cyprinid fishes of the river. Based on current study results, L. intermedius and L. nedgia might be omnivores in their diet but Labeobarbus forskalii seemed to be detritivorous.