Omnivorous Fish Research Articles

Feeding Habit-Specific Heavy Metal Bioaccumulation and Health Risk Assessment of Fish in a Tropical Reservoir in Southern China

Dietary uptake is well known as the predominant pathway of heavy metal bioaccumulation in organisms. Our study used a typical tropical reservoir and fish as a modeling system to test the hypothesis that feeding habits and living habitats significantly affect heavy metal bioaccumulation in fish. Specifically, Cr, Mn, Fe, Ni, Cu, Zn, Cd, and Pb concentrations in water, sediment, and fish, and δ13C and δ15N in 13 fish species were detected in the Songtao Reservoir of Hainan Province, southern China. Our results indicated that Zn concentration in carnivorous fish was higher than in omnivorous fish. Principal components analysis visually differentiated pelagic, benthopelagic, and demersal fish groups. Moreover, we found that the fish feeding in the demersal habitat showed higher heavy metal levels than those in the pelagic habitat. Additionally, the heavy metal contents in demersal fish were significantly positively correlated with sediments, while no positive correlation was observed in pelagic-feeding fish. The δ15N and the concentration of Ni, Zn in fish had a significantly positive correlation, suggesting the potential biomagnification. In contrast, Ni, Fe, Cu, and Cd negatively correlated with fish body weight/length, indicating the growth dilution effects. Finally, the estimated daily intake (EDI) of the metals was far below the provisional tolerable daily intake (PTDI), and target hazard quotients (THQ) were <1.0, indicating that the fish had no risk for consumption risks. Overall, our finding partially validated the hypothesis that the feeding habits and living habitats significantly influence heavy metal bioaccumulation in fish, which might be a broad generality for metal exposure scenarios in aquatic environments.

Heavy metals in fish, rice, and human hair and health risk assessment in Wuhan city, central China

The current study investigated the concentration of heavy metals (HMs) in human hair associated with fish and rice consumption in Wuhan City, central China. The mean values of As in 8/10 fish species exceeded the food safety standard of 0.015 mg/kg. The mean values (mg/kg) of HMs in rice followed a descending order of Zn (13.7)> Cu (1.9)>Cr (0.51)>As (0.11) >Cd (0.08) >Pb (0.04). The ascending order of HMs for male hair was Cd < As < Cr < Pb < Cu < Zn, while As < Cd < Cr < Pb < Cu < Zn for female. 30% of hair Cr and 22% of hair Zn contents exceeded the recommended values. The middle age (19–44) and adult (45–59) groups were the most vulnerable group, as the concentration for most elements was high in these age groups. A significant correlation was found between fish-eating frequency and hair Zn (r = 0.213; p < 0.05), and As (r = 0.204; p < 0.05). High odd ratios were found in a population with high fish-eating frequency, especially for Pb (7.19), As (3.1), Zn (3.83), and Cd (3.7). A significant non-carcinogenic risk was associated with Cr exposure through consuming herbivores, filter feeders, and omnivorous fish. The cancer risk values of Cd exposure (1.54E-04) via rice consumption and As exposure (1.25E-04) via consumption of omnivores fish indicate precautionary measures.

The Effect Of Different Feed Combinations On The Growth Rate, Efficiency And Survival Rate Of Juvenile Catfish (Clarias Sp.)

Catfish is classified as an omnivorous fish and has fast growth, has the ability to tolerate wide-ranging environmental parameters. The study aims to determine the length growth, weight growth, survival rate, feed efficiency and to determine the water duality in the Catfish (Clarias sp.) juvenile pond with differend feed treatments. The results of research showed that different feeding had an effect on the growth of catfish (Clarias sp.) juveniles. Length growth ranged from 9.78-10.8 cm, the highest value was in treatment 3, namely 10.8 cm and the lowest was in treatment 1, namely 9.78 cm. Weight growth ranged from 24-39 g, the highest value was in treatment 3, namely 39g and the lowest was in treatment 1, namely 24g. The survival rate ranged from 0.95-1%, the highest value was in treatment 3, namely 1% and the lowest was in treatment 1, namely 0.95%. feed efficiency ranged from 2.124-3.55%, the hinghest value was found in treatment 3, namely 3.55% and the lowest in treatment 1, namely 2.124%. the water quality during the research was still in the appropriate range for growth and survival of catfish (Clarias sp.) juveniles.

Diet changes thermal acclimation capacity, but not acclimation rate, in a marine ectotherm (Girella nigricans) during warming.

Global climate change is increasing thermal variability in coastal marine environments and the frequency, intensity and duration of marine heatwaves. At the same time, food availability and quality are being altered by anthropogenic environmental changes. Marine ectotherms often cope with changes in temperature through physiological acclimation, which can take several weeks and is a nutritionally demanding process. Here, we tested the hypothesis that different ecologically relevant diets (omnivorous, herbivorous, carnivorous) impact thermal acclimation rate and capacity, using a temperate omnivorous fish as a model (opaleye, Girella nigricans). We measured acute thermal performance curves for maximum heart rate because cardiac function has been observed to set upper thermal limits in ectotherms. Opaleye acclimated rapidly after raising water temperatures, but their thermal limits and acclimation rate were not affected by their diet. However, the fish's acclimation capacity for maximum heart rate was sensitive to diet, with fish in the herbivorous treatment displaying the smallest change in heart rate throughout acclimation. Mechanistically, ventricle fatty acid composition differed with diet treatment and was related to cardiac performance in ways consistent with homoviscous adaptation. Our results suggest that diet is an important, but often overlooked, determinant of thermal performance in ectotherms on environmentally relevant time scales.

The influences of spatial-temporal variability and ecological drivers on microplastic in marine fish in Hong Kong

This study examined microplastic (MP) occurrence and abundance in marine fish collected from the western and eastern waters of Hong Kong during the wet and dry seasons. Over half (57.1%) of the fish had MP in their gastrointestinal (GI) tracts, with overall MP abundance ranging from not detected to 44.0 items per individual. Statistical analysis revealed significant spatial and temporal differences in MP occurrence, with fish from more polluted areas having a higher likelihood of MP ingestion. Additionally, fish collected in the west during the wet season had significantly higher MP abundance, likely due to influence from the Pearl River Estuary. Omnivorous fish had significantly higher MP counts than carnivorous fish, regardless of collection location or time. Body length and weight were not significant predictors of MP occurrence or abundance. Our study identified several ecological drivers that affect MP ingestion by fish, including spatial-temporal variation, feeding mode, and feeding range. These findings provide a foundation for future research to investigate the relative importance of these factors in governing MP ingestion by fish in different ecosystems and species.

Nitrogen and phosphorus budgets of a polyculture system containing Penaeus vannamei, Siganus guttatus, and Selenotoca multifasciata

AbstractThe study was designed and conducted to optimize the structure of polyculture for Penaeus vannamei, Siganus guttatus (omnivorous fish), and Selenotoca multifasciata (carnivorous fish), and to compare the changes in yield, survival, and utilization rates of nitrogen (N) and phosphorus (P). Five treatments were performed as follows: Control (C) (0.0719 kg/m3, 0, 0), PSS1(0.0719 kg/m3, 0.0018 kg/m3, 0.0008 kg/m3), PSS2 (0.0719 kg/m3, 0.0033 kg/m3, 0.0016 kg/m3), PSS3 (0.0719 kg/m3, 0.0047 kg/m3, 0.0023 kg/m3), and PSS4 (0.0719 kg/m3, 0.0064 kg/m3, 0.0031 kg/m3) (with P:Penaeus vannamei, S:Siganus guttatus, and S: Selenotoca multifasciata). The yield and survival of P. vannamei in different treatments were significantly different (P&lt;0.05), with the highest yields being P. vannamei (718.75 kg/hm3), S. guttatus (32.97 kg/hm3), and S. multifasciata (15.63 kg/hm3) for treatment PSS2. The highest survival of P. vannamei was 89.4 ± 1.6% for treatment PSS2, while the highest N and P utilization rates were 27.7% and 37.5% for treatment PSS3. The polyculture mode when using a suitable density can improve production and survival of P. vannamei, as well as the utilization rates of N and P.

Historical analysis reveals ecological shifts in two omnivorous fish after the invasion of Limnoperna fortunei in the Uruguay river

Historical analysis reveals ecological shifts in two omnivorous fish after the invasion of Limnoperna fortunei in the Uruguay river

The feeding habits of small-bodied fishes mediate the strength of top-down effects on plankton and water quality in shallow subtropical lakes

The proliferation of small-bodied fishes in lakes is often accompanied by deterioration of water quality and ecosystem function. However, the potential impacts of different types of small-bodied fish species (e.g., obligate zooplanktivores and omnivores) on subtropical lake ecosystems in particular have been overlooked mainly due to their small size, shorter life spans and lower economic value. Therefore, we conducted a mesocosm experiment to elucidate how plankton communities and water quality respond to different types of small-bodied fishes, including a common zooplanktivorous fish (thin sharpbelly Toxabramis swinhonis) and other small-bodied omnivorous fishes (bitterling Acheilognathus macropterus, crucian carp Carassius auratus and sharpbelly Hemiculter leucisculus). During the experiment, the mean weekly total nitrogen (TN), total phosphorus (TP), chemical oxygen demand (CODMn), turbidity, chlorophyll-a (Chl.α) and trophic level index (TLI) values were generally higher in treatments where fish were present compared to treatments where fish were absent, but responses varied. At the end of the experiment, phytoplankton abundance and biomass and the relative abundance and biomass of cyanophyta were higher while the abundance and biomass of large-bodied zooplankton were lower in the fish-present treatments. Moreover, the mean weekly TP, CODMn, Chl.α and TLI values were generally higher in treatments with the obligate zooplanktivore, thin sharpbelly, when compared to treatments with omnivorous fishes. Also, the ratio of zooplankton to phytoplankton biomass was the lowest, and the ratio of Chl.α to TP was the highest in treatments with thin sharpbelly. Collectively, these general findings indicate that an overabundance of small-bodied fishes can have adverse effects on water quality and plankton communities and that small-bodied zooplanktivorous fishes likely induce stronger top-down effects on plankton and water quality than omnivorous fishes. Our results emphasise that small-bodied fishes should be monitored and controlled if overabundant when managing or restoring shallow subtropical lakes. From the perspective of environmental protection, the combined stocking of different piscivorous fish species that feed in different habitat types could be a way forward to control small-bodied fishes with different feeding habits, but more research is needed to assess the feasibility of this approach.

Mesopredator‐mediated trophic cascade can break persistent phytoplankton blooms in coastal waters

Managing eutrophied systems using only nutrient decreases to impose bottom–up control can be economically and ecologically challenging. Top–down controls through increased consumption have sometimes effectively controlled phytoplankton blooms. However, mechanistic insights, especially on possible trophic cascades, are less understood in brackish, species‐poor coastal waters, where large cladocera are absent. In this study, we set‐up large mesocosms for three consecutive years during the growing season. One set of mesocosms contained mesopredators (gobies and shrimps), whereas the other mesocosms had no such mesopredator present. The results were standardized to monitoring data from the ecosystem to track possible differences between treatments and the system. We found that mesopredator mesocosms showed lower turbidity, phytoplankton biomass and nutrients compared to no‐mesopredator mesocosms, and compared to the ecosystem. This decrease allowed macrophytes to colonize water depths only sparsely colonized in the ecosystem. Rotifer biomass increased in mesopredator mesocosms compared to the ecosystem and to the no‐mesopredator mesocosms. Likewise, copepod biomass that potentially grazes upon rotifers and other microzooplankton decreased in mesopredator mesocosms. No‐mesopredator mesocosms were colonized by an omnivorous mesograzer Gammarus tigrinus, potentially creating additional pressure on macrophytes and increasing grazing‐mediated nutrient release. Zooplankton was not able to control the non‐nutrient limited phytoplankton. We propose a new mechanism, where a higher mesopredator density will increase grazing on phytoplankton by promoting microzooplankton capable of grazing on picophytoplankton. This proposed mechanism would contrast with freshwater systems, where a decrease of zooplanktivorous fish would promote larger phytoplankton grazer like cladocera. Biomanipulation in such species‐poor eutrophic coastal waters may be more successful, due to less trophic pathways, that can cause complex top–down controls like in other systems. Stocking eutrophic coastal waters with gobies and shrimps may be an alternative biomanipulative approach rather than selectively removing large piscivorous or omnivorous fish from eutrophic coastal waters.

Comparative assessment of human health risk associated with heavy metals bioaccumulation in fish species (Barbus grypus and Tenualosa ilisha) from the Karoon River, Iran: Elucidating the role of habitat and feeding habits

Concentrations of Cd, Ni, and Pb were measured in the liver and muscle tissues of benthic omnivorous (Barbus grypus) and pelagic herbivorous (Tenualosa ilisha) fish collected from two sampling sites along the Karoon River, Khuzestan Province, southwest of Iran. Potential human health risks were evaluated by measuring the estimated daily intake (EDI), target hazard quotient (THQ), hazard index (HI), and target cancer risk (TR). The results highlight the important role of habitat and feeding habits in the uptake of HMs by the two species. The EDI for all HMs exceeded the oral reference doses (RfDo) provided by the USEPA, indicating the two fish species are not entirely safe for human consumption. The THQ values were within the permissible limit (< 1), while HI values (> 1) showed there was non-carcinogenic risk for consumers. The TR values for Pb were within the acceptable range (1.00E-06-1.00E-04) for both species.

Full-Fat Black Soldier Fly Larvae Meal in Diet for Tambaqui, Colossoma macropomum: Digestibility, Growth Performance and Economic Analysis of Feeds.

Black soldier fly (BSF, Hermetia illucens) larvae is a prominent ingredient in aquafeeds due to its high protein and energy contents. This study evaluated the digestibility of full-fat BSF larvae meal (FF-BSFL) and its inclusion in diets for tambaqui, Colossoma macropomum. The apparent digestibility coefficient of FF-BSFL for protein and energy was around of 88%, corresponding to 33.55% and 21.61 MJ kg-1 of digestible protein and energy, respectively. For the feeding trial, tambaqui juveniles (53.23 ± 1.07 g) were distributed in a completely randomized experimental design (n = 4; 150 L tanks; 10 fish per tank). Fish were fed diets including 0%, 5.25%, 10.50%, and 15.75% FF-BSFL to apparent satiation for 60 days. Fish fed 10.50% FF-BSFL dietary inclusion showed higher weight gain, feed intake, final biomass, and relative growth rate. The 10.50% FF-BSFL diet presented the highest index of economic profitability. Weight gain fitted a third-degree equation and the optimum FF-BSFL inclusion level was estimated at 11.6%. However, FF-BSFL dietary inclusion up to 15.75% did not impair growth fish performance. FF-BSFL seems to be a promising source of protein and energy for omnivorous fish aquafeed.

The use of Fermented Feed on the Growth of Tilapia (Oreochromis niloticus): A Review

Feed is the most important factor that must be considered for fish growth. Feed is also an important factor and affects the survival and growth of fish. The growth of tilapia is very dependent on physical and chemical influences and their interactions. Tilapia fish are included in omnivorous fish or all-eating. These fish can breed with a variety of foods, both animals and plants. Tilapia when it is still in the form of seeds, its food is plankton and moss, while when it is an adult, it can be given additional food in the form of artificial feed. The purpose of this study was to find out how the use of fermented feed on the growth of tilapia and the addition of fermented doses of 2% to 6%. The method used is a descriptive exploratory method from various previous research literature, both from national journals and international journals: Research Gate, Directory of Open Access Journals and Google Scholar. Fermentation is microbial activity in food to produce the desired product. Microbes that are generally involved in fermentation are bacteria, yeast and mold. Fermentation will simplify the particles in the feed ingredients so that it will increase the nutritional value of the feed. The results of the addition of fermentation to feed greatly affect the growth of tilapia with research giving doses of 2 to 6% fermented products with the highest growth, FCR and survival.

Potential health risk assessment of metals in the muscle of seven wild fish species from the Wujiangdu reservoir, China

Concentrations of Cu, Zn, Fe, Mn, Pb, Cd, As, and Hg were analyzed in the surface water and muscle of seven fish species (Carassius auratus, Cyprinus carpio, Hemiculter leucisculus, Pelteobagrus fulvidraco, Silurus meriaionalis, Ctenopharyngodon idellus, and Parabramis pekinensis) from the Wujiangdu reservoir, China. All metal concen-trations in water were lower than grade one water quality values. Mean metal concentrations in the fish muscle decreased in the order: Zn (10.765 mg kg−1) &gt; Fe (8.908 mg kg−1) &gt; Mn (0.373 mg kg−1) &gt; Cu (0.369 mg kg−1) &gt; Pb (0.158 mg kg−1) &gt; As (0.102 mg kg−1) &gt; Hg (0.042 mg kg−1) &gt; Cd (0.024 mg kg−1). Metal concentrations were higher in omnivorous and carnivorous fish than those in herbivorous fish. The bioconcentration factor (BCF) of Hg was much higher than that of other metals in all fish species. The values of target hazard quotient (THQ) and hazard index (HI) were lower than 1 for fishermen and the general population, indicating that there was no considerable noncarcinogenic risk. However, target cancer risk (TR) values were greater than 1.0 × 10−6, indicating that the car-cinogenic risk caused by fish consumption could not be ignored. Several kinds of fish species were not completely safe for human consumption according to the standard of the European Commission. The potential health risks in fishermen were much higher than that in the general population.

Seasonal Species Diversity and Dominance of Phytoplankton in Different types of tropical Domestic Sewage Oxidation Ponds

Planktons are small microscopic organisms, comprising diatoms and algae, which form the basis of primary production and the zooplankton, which are mainly crustaceans, rotifers and larval stages of larger animals. Both are the bio-indicators of a water body, constituting the main food for the carnivorous and omnivorous fishes in any aquatic ecosystem. In the present study, the species diversity, and their abundance with a total and average population of various species of phytoplankton have been studied in the primary and secondary domestic oxidation ponds along with a freshwater control pond situated at Shahpura. Bhopal, Madhya Pradesh, India. Physicochemical parameters like light penetration, water temperature, pH and DO were also analyzed along with the phytoplankton population in both types of ponds to assess their impacts. The samples were collected and identified using standard methods. The results revealed that the phytoplankton groups like Chlorophyceae, Bacillariophyceae, Cyanophyceae and Euglenophyceae were dominantly found in the sewage oxidation ponds along with about 20 species of phytoplankton in varying population densities in different seasons. A similar analysis was done in a freshwater control normal pond for comparison. Physicochemical parameters in these secondary sewage oxidation ponds with a high nutrient load were found to be highly favourable for the growth of the plankton species. A comparatively low number of phytoplankton was recorded in the freshwater control pond, which was highly deficient in nutrients.

Food and Feeding Habits of Eutropuis Niloticus in Lower River Benue, Makurdi

This study investigated the food and feeding habits of Eutropius niloticus in the lower River Benue to determine the diet composition in the stomach of E. niloticus and determine the dietary overlap. Fifty samples of the species were collected, and their stomach contents were analyzed by frequency of occurrence, numerical and volumetric methods. The IRI (Index of Relative Importance) was used to determine the stomach contents. The results showed that E. niloticus is an omnivorous fish that feeds on fish (IRI = 13.98%), crustaceans (IRI = 21.04, eggs/larvae (IRI = 14.78%), worms (IRI = 9.95%), insects (IRI = 11.52%), green algae (IRI = 0.87%), plant tissues (IRI = 1.15%), and plant seeds (IRI = 2.75%).

Spatial Heterogeneity of Food Webs in A River-Lake Ecotone under Flow Regulation – A Case Study in Northern China

The river–lake ecotone supports diverse aquatic life, but its food web structure and topology are poorly understood. Baiyangdian Lake, northern China’s largest shallow lake, depends on external environmental flows, of which the Fu River provides the most stable water supply. Here, we used stable isotopes and topological analysis to explore the food web structure along a spatial gradient using data from field surveys from 2018 to 2019. Carbon and nitrogen stable isotopes and the food web structure were associated with environmental factors for four ecosystem types (river, river mouth, lake mouth, lake). Detritus, phytoplankton, and zooplankton δ13C values became more depleted along the gradient from the river to the lake, whereas δ13C of submerged macrophytes was enriched in the ecotones compared to the river and lake. Higher δ15N values for basal resources and zooplankton occurred at the lake mouth and river mouth. The top consumers were omnivorous fish: Hemiculter leucisculus (trophic level [TL] = 3.85 ± 0.89) in the river and Pseudorasbora parva (TL = 4.54 ± 0.58) in the river mouth. Carnivorous Erythroculter dabryi occupied the highest TL (3.61 ± 0.36 and 4.46 ± 0.36, respectively) in the lake mouth and lake. These results together led to a change from a detritus-based to phytoplankton-based food web along the gradient from the river to the lake. The species richness, number of trophic links, link density, and mean food chain length all are greatest in the lake, followed by the lake mouth, and the lowest were in the river. Our results provide a holistic view of the ecotone ecosystem and its food web, suggesting that it supports a more diverse species assemblage and more complex food web structure than the adjacent river ecosystem, rather than the adjacent lake ecosystem. Therefore, management should emphasize the combined effects of altered hydrological regimes and poor water quality on the ecotone food webs to manage the river and lake more sustainably.

Water-level fluctuations lead to changes in the diet of an omnivorous fish in a floodplain

Abstract The hydrological regime leads to fluctuations in the availability of food resources for fish, which may reflect in their diet variation. Our main goal was to analyze the relationship between water-level fluctuations and the diet and the body condition of Trachelyopterus galeatus in the Upper Paraná River floodplain. The fish used in the study were sampled quarterly along nine years, at nine sampling stations. Our results showed that diet of T. galeatus varied in response to oscillations in the hydrometric level, with the consumption of terrestrial invertebrates being positively related to hydrometric level, while the consumption of aquatic invertebrates was negatively related. The trophic niche breadth and feeding activity were not affected by hydrometric level, but the fish body condition was positively affected. The high food plasticity allows T. galeatus to consume the most available resources (e.g., terrestrial invertebrates in high water levels), which probably contributed to the increase in its body condition in higher hydrometric levels. In summary, the hydrological dynamic is fundamental for the diet variation of omnivorous fish, which can take advantage of the resource availability according to the hydrometric level, increasing its body condition when allochthonous resources as terrestrial invertebrates are supposed to be more available.

Fish as bio-indicator tool for assessing estuarine health

Fish Health Index and Index of Biotic Integrity directly indicates environmental health and was used in our monitoring at Coleroon, Vellar and Uppanar, estuaries in the southeast coast of India. The use of cast nets revealed 104 species of fish that belongs to 69 genera, 44 families and 10 orders. Assessment using fish health index at Coleroon, Vellar and Uppanar estuaries produced scores of 4.8692, 8.4981 and 1.4042 which means Vellar has better health than Coleroon and Uppanar. In addition, 12 metrics were used to produce the index of biotic integrity where total scores varied from 18 to 51. With Vellar achieving higher scores than Coleroon and Uppanar estuary, a Two-way ANOVA was employed to validate the data with significant achievement (P&lt;0.005). Therefore, we can safely associate Coleroon, Vellar and Uppanar with ‘Fair’, ‘Good’ and ‘Very poor’ grades. Also, visual depiction of Vellar demarcates it as pristine in comparison to Coleroon and Uppanar that are subject to impairments along with dominance of omnivorous fishes. Knowledge from this study eases monitoring of important estuaries particularly for food security so that management sustains community livelihood.

Microplastics in fishes in amazon riverine beaches: Influence of feeding mode and distance to urban settlements

Microplastic (MP) pollution is a global problem and has affected several biological levels even in protected areas. In the present study, MP contamination was investigated in fish associated with sandy beaches in a permanent environmental protection area in the Amazon. In order to achieve this goal, the shape, color, abundance, richness, and chemical composition of MPs in the digestive tract of 29 fish species in 24 beaches of the Machado River, western Brazilian Amazon, were evaluated. Linear mixed models (LMMs) were adjusted to test the effects of local human modification (HMc), distance from urban settlements, distance from the closest affluent, and trophic categories of fish species on microplastic abundance and richness in their digestive tracts. From the 1082 fish analyzed, 332 (30 %) presented MPs in their digestive tracts. A total of 617 MPs was found (1.8 ± 1.6 MPs; 4.5 ± 1.9 MPs/g fish). Omnivorous and insectivorous fish presented more MPs in sandy beaches located closer to urban settlements. However, carnivorous fish presented a higher abundance of MPs in their digestive tracts compared with the other trophic guilds. This is the first study to analyze plastic contamination in fish associated with sandy beaches in the Amazon (Brazil), and it revealed contamination of the ichthyofauna mainly related to the distance from urban settlements. Our results reinforce the need for better management of landscape surrounding protected areas to mitigate MP pollution.

Experimental assessment of 241Am accumulation in Carassius gibelio from amphipods

Accumulation of dietary 241Am in freshwater omnivorous fish (Carassius gibelio) was studied aiming to estimate the distribution and retention of 241Am in the fish body. Amphipods labeled with 241Am served as a food item. From 0.4 to 0.6% of ingested 241Am was retained in the fish body after short courses of feeding and depuration, the trophic transfer factor of 241Am for whole organism level was about 2∙10−4.