Fish Flesh Research Articles

Trace metals and nutrient analysis of marine fish species from the Gwadar coast

Trace metals are naturally occurring metals found in very small concentrations in the environment. In the context of fish flesh, metals such as copper, calcium, potassium, sodium, zinc, iron, and manganese are absorbed by fish and play vital roles in various physiological functions. However, if these metals exceed the recommended limits set by WHO/FAO, they are termed 'toxic metals' due to their harmful impacts on both the fish and its consumers. Therefore, the present study aims to analyze the levels of protein, lipids, and certain metals—Aluminum (Al), Sodium (Na), Zinc (Zn), Titanium (Ti), Iron (Fe), Copper (Cu), Potassium (K), and Calcium (Ca) in three commercially important marine fishes i.e. Rastrelliger kanagurta, Sardinella abella, and Otolithes ruber. The study also aims to assess their potential impact on human health. The macro-Kjeldhal method and Soxhlet apparatus were used to estimate protein and lipid contents, while atomic absorption spectroscopy (AAS) was used to estimate trace metals found in fishes. The study found that these fish species are valuable sources of protein, lipids, and certain essential minerals. The protein content (CP) in these three species ranged from 63.35 to 86.57%, while lipid content was from 21.05 to 23.86%. The overall results of the trace metal concentrations analyzed in the present study revealed that Aluminum (Al), Sodium (Na), Zinc (Zn), Titanium (Ti), Copper (Cu), Potassium (K), and Calcium (Ca) were found in low concentration or traces and also within suitable ranges as set by WHO/FAO. However, Iron (Fe) was absent in all three species. Moreover, both copper and potassium were found in all three species, while Zinc was present in Rastrelliger kanagurta and Sardinella abella, calcium in Sardinella abella, and sodium in Otolithes ruber only. Titanium was recorded for the first time in S. abella. However, the total health risk assessment associated with these fish food consumption was measured by THQ and TTHQ and found to be less than 1, which shows no potential risk related to trace metals found in these fishes on human health upon their consumption. In conclusion, these commercially important marine fish species were found valuable sources of protein, lipids, and essential trace minerals that are necessary for human health. Thus, the current study provides useful information for the local population to make informed decisions about their daily diets and highlights the importance of sustainable fishing practices to maintain these valuable marine resources by periodical monitoring of their ecosystem.

Out of sight, out of mind: how pescetarians manage dissonance by creating distance

ABSTRACT For many, there exists a cognitive inconsistency between the practice of eating non-human animals and the belief that animals are morally relevant. This juxtaposition has fittingly been described as the ‘meat paradox’. However, what can be said about the decision to eat only the flesh of fish? The present research seeks to understand what attitudes lead pescetarians to remove terrestrial animals from their plate but still include aquatic animals such as fish. Semi-structured interviews were conducted with self-identifying pescetarians and analysed using reflexive thematic analysis. Three themes are presented which can be understood by reference to the construal-level theory of psychological distance. Fish were perceived as distant on multiple dimensions which resulted in speciesist (the idea that some species are more important and morally relevant than others) attitudes toward marine animals’ capabilities and the justification of pescetarianism as a compromise between debates of feasibility and ethical desirability.

Insights into the fish protein degradation induced by the fish-borne spoiler Pseudomonas psychrophila and Shewanella putrefaciens: From whole genome sequencing to quality changes

The aim of this study is evaluating the protein degradation capacity of specific spoilage organisms (SSOs) Pseudomonas psychrophila and Shewanella putrefaciens in fish flesh during chilled storage and revealing the underlying genes by whole-genome sequencing (WGS). Biochemical and physical tests were performed on fish flesh inoculated with P. psychrophila and S. putrefaciens individually, including textural properties, myofibrillar fragmentation index, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles, free amino acid composition, total volatile basic nitrogen (TVB-N), trichloroacetic acid (TCA) soluble peptides, and muscle microstructure. Results showed that P. psychrophila and S. putrefaciens exhibited a strong capacity for decomposing the fish protein, and the deterioration of fish flesh texture was primarily attributed to P. psychrophila. The genes from SSOs associated with the production of proteases were identified by whole genome sequencing and serine protease may be the primary enzyme secreted by SSOs involved in the degradation of fish protein. Therefore, the present study has shed light on the mechanisms of protein degradation induced by SSOs, thereby offering valuable insights for the development of effective quality control strategies.

Development of a new method for extracting histamine from marine fish flesh using the salting-out technique.

A simple and practical method was developed to extract histamine from fish products using sodium chloride (NaCl). After obtaining a saline extract from fish samples, histamine was derivatized by a condensation reaction with ortho-phthalaldehyde. Fluorescence intensity was measured by a fluorimeter. The first part of this work concerned a solid-liquid extraction tested with samples from the food analysis performance assessment scheme. The best histamine extraction yield (97%) was obtained using an extraction time of 4 minutes, a temperature of 40°C, and a NaCl/water ratio of 41% (w/w). The second part focused on a liquid-liquid extraction carried out on standard solutions of histamine (45, 90, and 180 mg/kg). The use of NaCl (41%) and trichloroacetic acid [(TCA) 10%] did not show any significant difference in extraction yield. The yield obtained was 99.15-100.1% for TCA (10%) and 98.65-99.45% for NaCl (41%). The validation criteria (repeatability and reproducibility) were checked by evaluating the reliability of the method. Extraction using NaCl has proven to be an interesting alternative method for the extraction of histamine from fish, as it is reliable, inexpensive, and less hazardous.

Determination of Heavy Metals in Etroplus suratensis from Koggala Lagoon in Southern, Sri Lanka

Fish is one of the best organisms in many scientific studies to evaluate heavy metal pollution and human health hazards as they are well-understood organisms in the aquatic environment. The present study was carried out to examine the level of heavy metals in different tissues of Etroplus suratensis (Green chromide) in Koggala lagoon, Sri Lanka. Atomic absorption spectrophotometer (AAS) was used to determine the levels of copper (Cu2+), cadmium (Cd+3), lead (Pb+2) and Chromium (Cr+3) ions in the different tissues (skin, liver, gill, and flesh) of fish belonging to three different sizes; small (7.8-10.2) cm, medium (14.1-16.6) cm, and large (19.8-25.2) cm. The number of thirty-six fish were collected from the lagoon randomly. According to available sizes, 12 fish for each size class were used for the analysis. Furthermore, the histological analysis was carried out to identify the changes at the tissue levelling the gill and liver of fish in three different size classes. Heavy metal concentration in fish samples were compared with the standard levels of heavy metals. Heavy metal concentrations in body tissues of three different body sizes of fish were found to be mainly in the order of Cu>Pb>Cr> Cd. The highest concentrations (P<0.05) of heavy metals were found in the fish flesh and skin, while the lowest concentrations were found in the gills. The range of heavy metal concentrations (g g-1 dry weight) in body tissue of small size, E. suratensis fish were, Cu: 0.0443-0.6210, Cd: 0.0110–0.0214, Pb: Below Detection Level (BDL)- 0.46 and Cr: BDL-39.633, Medium size fish were, Cu: 0.0713–0.6210, Cd: 0.0134-0.0170, Pb: BDL-40.906, Cr: 0.0014–0.0500 and large fish were, Cu: 0.0553–0.345, Cd: 0.0110–0.0256, Pb: 0.0204–0.2103 and Cr: 0.0194–0.0773. However, Cd, Cr and Pb concentrations of flesh tissues were under the standard recommended limits referred by the FAO. Through the Cu concentration in flesh, tissues exceeded the standard limits of FAO. It is not considered as a toxic heavy metal. Histological analysis revealed that the deviation of shape of hepatic cells in the liver may due to the exposure to heavy metals in the lagoon. According to the overall result, biomagnification nature of heavy metals, and the consumption of E. suratensis in the Koggala the bioaccumulation and lagoon may create health hazards to consumers. 
 Keywords: Green chromide, Koggala Lagoon, Heavy metals, Histology

Assessment of Full-Fat Tenebrio molitor as Feed Ingredient for Solea senegalensis: Effects on Growth Performance and Lipid Profile.

Tenebrio molitor (TM) is considered as one of the most promising protein sources for replacing fish meal in aquafeeds, among other things because it is rich in protein, a good source of micronutrients and has a low carbon footprint and land use. However, the main drawback of TM is its fatty acid profile, in particular its low content of n-3 PUFA. This study evaluates the effects of partially replacing plant or marine-derived with full-fat TM meal at two different levels on growth performance and lipid profiles of Senegalese sole (Solea senegalensis). For this purpose, a control diet (CTRL) and four experimental isoproteic (53%) and isolipidic (16%) diets were formulated containing 5 and 10% TM meal replacing mostly fish meal (FM5 and FM10), or 10 and 15% TM meal replacing mostly plant meal (PP10 and PP15). Fish (215 g) were fed at 1% of their body weight for 98 days. The final body weight of fish fed the experimental diets containing TM meal was not different from that of fish fed the CTRL diet (289 g). However, the inclusion of TM meal resulted in a gradual improvement in growth rate and feed efficiency in both cases (replacement of fish or plant meals), and significant differences in specific growth rate (SGR) were observed between fish fed the CTRL diet (SGR = 0.30% day-1) and those fed diets with the highest TM meal content (PP15; SGR = 0.35% day-1). The experimental groups did not show any differences in the protein content of the muscle (19.6% w/w). However, significant differences were observed in the total lipid content of the muscle, with the FM10, PP10, and PP15 groups having the lowest muscle lipid contents (2.2% ww). These fish also showed the lowest neutral lipid content in muscle (6.6% dw), but no differences were observed in the total phospholipid content (2.6% dw). Regarding the fatty acid profile, fish fed FM10, PP10 and PP15 had lower levels of linoleic acid (18:2n-6) and higher levels of oleic acid (18:1n-9) in liver and muscle compared to fish fed CTRL. However, no differences were found between fish fed CTRL and TM-based diets for docosahexaenoic acid (22:6n-3) and total n-3 PUFA in liver and muscle. In conclusion, our study demonstrated that full-fat TM inclusion up to 15% in S. senegalensis diets had no negative effects or even some positive effects on fish survival, growth performance, nutrient utilization and flesh quality.

Assessing organophosphate insecticide retention in muscle tissues of juvenile common carp fish under acute toxicity tests

Organophosphate insecticide spray poses potential threat of contamination of environmental components their accumulation in aquatic organisms. Although various physiological deficits associated with their exposure in fishes are documented, yet their retention in their edible muscle tissues has been poorly studied. In this context, the study was undertaken to ascertain the bioaccumulation of two organophosphate insecticide compounds (dimethoate and chlorpyrifos) in the muscles of juvenile Cyprinus carpio. The study could provide insight into the risks to human health associated with consuming contaminated fish flesh. The fishes exposed to various concentrations of dimethoate and chlorpyrifos in-vivo for 96 to ascertain the uptake and retention of these insecticides in the muscle. Results indicated that fish muscles accumulated the residues at all the concentrations with the recovery of 2.99% (0.032 ppm) of dimethoate exposed to LC50 concentrations. In contrast, the chlorpyrifos residues were found Below the Detection Level (BDL) in the fishes exposed to LC50 concentrations. The percentage bioaccumulation of dimethoate in fish muscle was 88.10%, and that of chlorpyrifos was BDL. The bio-concentration factor was dose-dependent and increased with increasing doses of both insecticides. The study invites attention to human health risk assessment in the regions where contaminated fish are consumed without scientific supervision.

Seasonal determination of proximate composition and essential elements in commercial fishes from Pakistan and human health risk assessment

The seasonal variability in proximate composition and essential elements demonstrates that the habitat and feeding habits of fish species play a vital role in energy transfer.
 We aimed to ascertain seasonal variability in the biochemical composition (protein, lipids, carbohydrates, ash, and moisture) and the amounts of Na, K, Ca, Mg, Mn, and Zn in the species Nemipterus japonicus, Epinephelus erythrurus, Nematalosa nasus, and Ilisha striatula inhabiting pelagic and demersal zones. We compared the nutritional profile of these fish species and their seasonal importance. The essential elements were detected by flame atomic absorption spectrometry and found in the following order: K > Na > Ca > Mg > Mn > Zn. To determine the proximate composition, we employed a number of methods: the Lowry method for protein analysis, the acid hydrolysis method for fat/lipid analysis, a formula for carbohydrates and moisture, and the incineration method for ash content.
 The spring inter-monsoon season showed the highest values for the essential elements in both pelagic and demersal species. However, the pelagic species had the highest biochemical composition levels during the southwest monsoon. The autumn intermonsoon had the lowest bio-profile for the fishes of both regimes.
 The summer season, which is not thought to be good for fish consumption, showed the highest biochemical composition levels in the pelagic fish. The nutritional profile of fish flesh can be affected by feeding habits, seasonal variation, and habitat.

Antimicrobial resistance, virulence profile, and genetic analysis of ESBL-producing Escherichia coli isolated from Nile tilapia in fresh markets and supermarkets in Thailand.

This study investigated the prevalence and antimicrobial resistance (AMR) of Escherichia coli (E. coli) in Nile tilapia from fresh markets and supermarkets. A total of samples (n = 828) were collected from Nile tilapia including fish flesh (n = 276), liver and kidney (n = 276), and intestine (n = 276). Overall prevalence of fecal coliforms (61.6%) and E. coli (53.0%) were observed. High prevalence of E. coli was found in the intestine (71.4%), followed by the liver and kidney (45.7%). The highest prevalence of resistance was commonly found against tetracycline (78.5%), ampicillin (72.8%), and sulfamethoxazole (45.6%) with resistance to only tetracycline (15.2%) as the most common antibiogram. The prevalence of multidrug resistance (MDR) (54.4%) and Extended-spectrum beta-lactamases (ESBLs) (5.7%) were examined. The predominant virulence genes (n = 158) were st (14.6%), followed by eaeA (0.6%). The blaTEM (73.4%), tetA (65.2%), and qnrS (57.6%). There is statistical significance between Nile tilapia from fresh markets and supermarkets. Based on logistic regression analysis, ampicillin-resistant E. coli was statistically associated with the phenotypic resistance to tetracycline and trimethoprim, and the presence of blaTEM and tetA (p < 0.05). Further investigation of AMR transference and their mechanisms is needed for AMR control.

Optimization of soybean oil content in a soybean oil-based aquafeed for grass carp (Ctenopharyngodon idella) to achieve optimal growth performance, proximate and fatty acid compositions, and lipid metabolism

Soybean oil (SO), an important plant-derived lipid, is routinely used in aquafeed as a partial substitute for fish oil. However, the effect of various contents of SO in a SO-based aquafeed on specific aquatic animals and the underlying mechanisms are unclear. In this study, five isonitrogenous diets containing different SO contents (0 %, 3 %, 6 %, 9 %, and 12 %, named as S0, S3, S6, S9, and S12, respectively) were prepared with SO as the predominant lipid source, and 12-week feeding experiments were conducted on juvenile grass carp (Ctenopharyngodon idella) (initial weight: 12.54 ± 0.08 g). Apart from lower feed conversion ratio in the S6 and S9 groups (P < 0.05), no obvious changes were observed in other growth indices (e.g., final weight and weight gain rate) in grass carp fed on diets with 0–9 % SO (P > 0.05). The S12 group exhibited significant decrease in the final weight and weight gain rate and increase in the viscerosomatic index (P < 0.05). Unlike gradual decrease in moisture, ash, and saturated fatty acid contents, muscle crude fat and unsaturated fatty acid (particularly polyunsaturated fatty acid) contents significantly increased with the increasing SO contents (P < 0.05). Serum triglyceride contents continuously increased with the increasing SO amounts, exhibiting the maximum value in the S12 group (P < 0.05). Similarly, the S12 group displayed the highest levels of aspartate aminotransferase, alanine transaminase, low-density lipoprotein cholesterol, and total cholesterol in serum (P < 0.05). Only the S12 group exhibited scanty lymphocytic infiltration in some areas of the hepatopancreas. However, other groups exhibited no obvious histopathological abnormalities. Lipogenic genes (dgat, fad, elovl1, elovl6, elovl7, lpcat, and pla2), ACSL family members (acsl1a, acsl1b, acsl3, acsl4, acsl5, and acsl6), lipolytic genes (atg1, cpt1a, cpt1b, hsl, and lpl), fatty acid transport-related genes (cd36, fabp, and fatp), and transcription factor involved in lipid metabolism (ppar α) were gradually upregulated as dietary SO content increased (P < 0.05). However, the transcript levels of srebp1 and its target gene acc1 exhibited decreasing trend under the same conditions, and significant downregulation of ppar γ was observed in the S12 group (P < 0.05). In conclusion, the optimal content of SO as the main lipid source in a SO-based diet for juvenile grass carp ranged from 6 % to 9 %, at which growth requirements of grass carp were met and fish health and fillet quality were effectively maintained. Our data provided a scientific reference for developing more efficient aquafeed formulations and enhancing fish flesh quality in aquaculture, as well as provided basic information for further assessing the regulatory mechanism of lipid homeostasis in teleost fishes.

Evaluation of antibiotic use and analysis of ciprofloxacin and gentamicin residue in fish samples from farms in Lagos, Nigeria.

Antibiotic use in aquaculture for increase yield has been established over time; however, consumption of such fish may lead to inadvertent intake of sub therapeutic doses of antibiotics. Therefore, this study aimed to investigate the extent of antibiotic use in fish farming and ciprofloxacin and gentamicin residues in fish that are consumed in Lagos, Nigeria. It was conducted in two parts: a survey of 60 fish producers to assess their use of antibiotics and an analysis of ciprofloxacin and gentamicin residues in fish organs using high-performance liquid chromatography (HPLC). The survey found that twenty-nine (48%) of the farms used antibiotics, with oxytetracycline being the most common (20%), followed by ciprofloxacin (15%); gentamicin (5%); neomycin (8.33%); and probiotics (13%). HPLC analysis of fish liver and fillet samples showed that Lagos Island had the lowest residual ciprofloxacin dose (0.3014ug/g), while Lagos mainland had the greatest residual ciprofloxacin dosage (113.78765ug/g). The mean gentamicin residue in flesh of fish from farms in Lagos Island LGA was 0.37ug/g while that obtained for liver of fish samples from Surulere LGA was 2.12ug/g). The largest (5.3240ug/g) and lowest (0.2661ug/g) residual gentamicin antibiotic concentrations were found in fishes harvested from farms located in Surulere and Lagos Island, respectively. The residue levels were within the permitted range set by the WHO, but continuous regulatory surveillance is necessary to prevent antimicrobial resistance spread and improved food safety. The study has revealed that fish produced in the study area contained residues of the commonly used antibiotics hence farmers should be encouraged to consult veterinarians in cases of disease treatment for judicious use of antibiotics while self-medication and purchase of antibiotics from vendors should be discouraged.

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.

Universal Method for Determination of Ciguatoxins by LC-MS/MS

Ciguatera poisoning (CP) is one of the most frequent seafood poisonings across the globe. CP results from the consumption of fish flesh that has accumulated principal toxins known as ciguatoxins (CTXs), and it mainly occurs in tropical and subtropical regions. In Japan, incidents of CP have been reported primarily from Okinawa and Amami Islands in the subtropical area. Meanwhile, there have also been reports from Mainland sporadically. Since the amount of CTXs contained in fish flesh is extremely low, a highly sensitive detection method by LC-MS/MS is required. But the currently reported detection method is applicable only to specific equipment, and many laboratories have difficulty to respond CP. In this study, to prepare for the risk of nationwide CP, we researched a universal analytical method for CTXs based on LC-MS/MS. Using a water/acetonitrile mobile phase supplemented with lithium hydroxide and formic acid gave rise to prominent peaks of the stable [M+Li]+ions. As the [M+Li]+ions did not produce valid product ions even with high collision energy, the [M+Li]+ions of each analog were set for both precursor and product ions ([M+Li]+>[M+Li]+) and monitored under the multiple reaction monitoring (MRM) mode. With the method described above, analyses of nine CTX congeners were carried out. The limit of detection (LOD, S/N>5) and quantitation (LOQ, S/N>10) were estimated as 0.005-0.030 ng/mL and 0.010-0.061 ng/mL, respectively. When the 1 mL of extract solution is prepared from 5 g of the fish tissue, the LOD and LOQ will be at 0.001-0.006 μg/kg and 0.002-0.012 μg/kg, respectively. This result indicates that we could detect the required level of 0.175 μg/kg CTX1B equivalent in fish flesh which is recommended for safe consumption in Japan. This method is considered to be a universal analytical method without depending on the specific equipment. Thus it could contribute to improving the CP investigations in nationwide laboratories.

Effectiveness of cleanup and dredging operations on some heavy metal residues in fish flesh from Manzala lake, Egypt

Effectiveness of cleanup and dredging operations on some heavy metal residues in fish flesh from Manzala lake, Egypt

Isolation of Lactic Acid Bacteria Eliminating Trimethylamine (TMA) for Application to Fishery Processing.

Fishy odor of fish flesh (meat) presents a severe problem for marine production. The main cause of fishy odor is trimethylamine (TMA), which increases during storage. It is produced from trimethylamine oxide (TMAO), an osmosis-regulating substance in fish cells that functions by a reduction reaction. Bacterial growth in fish meat increases TMA. Its odor reduces the commercial value of the meat. Technologies for its regulation and elimination are desired. This chapter presents a description of the use of lactic acid to eliminate TMA. The lactic acid is producible safely by bacteria during food processing using picric acid-toluene.A method of eliminating TMA was demonstrated using Lactobacillus plantarum H78. Furthermore, an assay method was explained for reducing TMA in fish meat by fermenting the H78 strain.

Deep machine learning identified fish flesh using multispectral imaging

Food fraud is widespread in the aquatic food market, hence fast and non-destructive methods of identification of fish flesh are needed. In this study, multispectral imaging (MSI) was used to screen flesh slices from 20 edible fish species commonly found in the sea around Yantai, China, by combining identification based on the mitochondrial COI gene. We found that nCDA images transformed from MSI data showed significant differences in flesh splices of the 20 fish species. We then employed eight models to compare their prediction performances based on the hold-out method with 70% training and 30% test sets. Convolutional neural network (CNN), quadratic discriminant analysis (QDA), support vector machine (SVM), and linear discriminant analysis (LDA) models perform well on cross-validation and test data. CNN and QDA achieved more than 99% accuracy on the test set. By extracting the CNN features for optimization, a very high degree of separation was obtained for all species. Furthermore, based on the Gini index in RF, 11 bands were selected as key classification features for CNN, and an accuracy of 98% was achieved. Our study developed a successful pipeline for employing machine learning models (especially CNN) on MSI identification of fish flesh, and provided a convenient and non-destructive method to determine the marketing of fish flesh in the future.

A pilot study on the isolation and identification of histamine-producing bacteria from narrow barred Spanish mackerel and Japanese thread fin bream from Ukkadam fish market, Coimbatore, India

Consumption of marine fishes with high histamine levels due to improper storing leads to cause scombroid or histamine fish poisoning. In spoiled fishes, bacteria begin to break down the histidine into histamine by decarboxylation activity. Previous studies reported that black muscle fishes usually produce large amounts of histamine-producing bacteria (HPB). In this study, two white muscle fishes such as Scomberomorus commerson (Narrow-barred Spanish mackerel) and Nemipterus japonicus (Japanese threadfin bream) were chosen to detect the presence of histamine-producing bacteria (HPB). The fish samples were purchased from Ukkadam fish market in Coimbatore and examined for the occurrence of HPB on Niven agar. The isolated HPB on media were analyzed for identification based on their morphological characteristics, primary test, and biochemical test. Finally, 8 colonies were confirmed as the cause for histamine production of both fishes and among them, 5 belong to the family Enterobacteriaceae and others belong to the family Aeromonadaceae, Morganellaceae, and Enterococcaceae. Our study showed that the histamine-producing bacteria highly reported in dark-muscle fishes were also isolated from the chosen white-muscle fishes. Hence the presence of HPB indicates the improper maintenance of fish in retail fish markets. This considerable incidence of histamine-producing bacteria which on proliferation under suitable conditions may contribute to toxic histamine accumulation in the flesh of fishes.

Phytobiotics: Response to Aquaculture as Substitute of Antibiotics and other Chemical Additives

The use of phytobiotics in aquafarming is nowadays an interesting topic because of its eco-friendly nature for the growth and antimicrobial performance of aqua livestock. Currently, the use of various antibiotics in aquaculture are restricted due to concerns about the potential development of antibiotic-resistant pathogenic bacteria. Overuse of antibiotics and other chemicals (like different disinfectants, chemicals, and preservatives) increases the potentiality of residual antibiotics and other chemicals being present in fish, fish flesh as well as in fishery products. Various phytobiotics from plant extracts or direct plant or animal resources have changed the present traditional scenario of using an antibiotic component against livestock performance in aquaculture. The bioactive compounds (like alkaloids, tannins, saponins, glycosides, terpenoids, phenolics, flavonoids, essential oils, or steroids) present in the phytobiotics act as an immunity booster, growth promoter, bio-appetizer, reproductive stimulator, bio-preservatives, etc. So, phytobiotics becoming an effective additive in aquaculture as a substitute for antibiotics and other chemical components. This present article is designed to provide a comprehensive and insightful overview of the current state of knowledge about phytobiotics that supports the need for sustainable and environmental friendly practices in the context of aquaculture.

Tissue Distribution and Metabolization of Ciguatoxins in an Herbivorous Fish following Experimental Dietary Exposure to Gambierdiscus polynesiensis.

Ciguatoxins (CTXs), potent neurotoxins produced by dinoflagellates of the genera Gambierdiscus and Fukuyoa, accumulate in commonly consumed fish species, causing human ciguatera poisoning. Field collections of Pacific reef fish reveal that consumed CTXs undergo oxidative biotransformations, resulting in numerous, often toxified analogs. Following our study showing rapid CTX accumulation in flesh of an herbivorous fish, we used the same laboratory model to examine the tissue distribution and metabolization of Pacific CTXs following long-term dietary exposure. Naso brevirostris consumed cells of Gambierdiscus polynesiensis in a gel food matrix over 16 weeks at a constant dose rate of 0.36 ng CTX3C equiv g-1 fish d-1. CTX toxicity determination of fish tissues showed CTX activity in all tissues of exposed fish (eight tissues plus the carcass), with the highest concentrations in the spleen. Muscle tissue retained the largest proportion of CTXs, with 44% of the total tissue burden. Moreover, relative to our previous study, we found that larger fish with slower growth rates assimilated a higher proportion of ingested toxin in their flesh (13% vs. 2%). Analysis of muscle extracts revealed the presence of CTX3C and CTX3B as well as a biotransformed product showing the m/z transitions of 2,3-dihydroxyCTX3C. This is the first experimental evidence of oxidative transformation of an algal CTX in a model consumer and known vector of CTX into the fish food web. These findings that the flesh intended for human consumption carries the majority of the toxin load, and that growth rates can influence the relationship between exposure and accumulation, have significant implications in risk assessment and the development of regulatory measures aimed at ensuring seafood safety.

Evaluation of a Calcium Carbonate-Based Container for Transportation and Storage of Fresh Fish as a Sustainable Alternative to Polystyrene Boxes

The present study aimed to assess the effect of alternative packaging materials on the quality retention and shelf-life of whole fish under low and abuse temperature conditions. Red sea bream (Pagrus major) was harvested and stored in different packaging containers, i.e., a conventional polystyrene (PS) box, a CaCO3-based box and a cardboard box (tested as a simple alternative container for transportation and short-term storage of food). After harvesting and transportation, fish was stored in the tested containers at 2 °C for 11 days and periodically kept at room temperature (25 °C) to simulate potential temperature fluctuations in the actual supply chain. The effect of temperature fluctuations and packaging materials on the quality and remaining shelf-life of fish was determined by microbial enumeration (total viable counts, Pseudomonas spp. and Enterobacteriaceae). PS retained fish quality and maintained a low temperature of fish for longer periods of time during storage at ambient conditions. The CaCO3-based containers also showed satisfactory performance, resulting in a similar microbial load in fish flesh to the samples stored in PS boxes after 11 days of simulated transportation and storage (TVC load 7.8–8.0 logcfu/g). Cardboard resulted in a rapid increase in the internal temperature during the temperature fluctuations at ambient conditions, resulting in higher microbial loads of fish flesh at all stages of the simulated cold chain. The replacement of conventional plastic packaging materials with alternative, environmentally friendly packaging systems without affecting the shelf-life of fish may reduce plastic waste while ensuring the high quality and shelf-life of perishable food products.