Fatty Acid Composition Of Fish Research Articles

Effect of some local plant extracts on fatty acid composition of fish (Alestes baremoze) during smoking and sun drying in the Far-North region of Cameroon.

The objective of this study was to assess the antioxidant activities of three plant extracts (Moringa oleifera leaves, Xylopia aethiopica fruits, and Allium cepa leaves) and to evaluate their effects on the preservation of fish polyunsaturated fatty acids (PUFAs) during smoking and sun-drying processes. PUFAs are highly prone to oxidation during fish processing. The plant extracts were analyzed for their polyphenol contents and were evaluated for their total antiradical capacity. The polyphenol components of each plant were characterized. The hydroethanolic and aqueous extracts were added to the fish at concentrations of 3, 6, 9, and 12 g/L and 10, 20, 30, and 40 g/L, respectively. Butylated hydroxytoluene (BHT) was used as a positive control at a concentration of 2 g/L to compare the antioxidant effects of the plant extracts. The treated fish was subjected to smoking or sun drying and the fatty acid composition of the fish lipid extract was assessed. The results showed that the total polyphenolic, flavonoid, and tannin contents varied significantly from one plant extract to the other (p < .05). The radical scavenging and FRAP increased significantly with the concentration of the plant extracts (p < .05). An HPLC analysis of the extracts led to the preliminary identification of four hydroxycinnamic acids in M. oleifera and X. aethiopica, one anthocyanin and one flavone glycoside in M. oleifera, and four flavan-3-ols in X. aethiopica. Moreover, eight flavonols were preliminarily identified in the three plants. Compared to the control product, these plant extracts significantly protected fish PUFAs from oxidation (p < .05). The aqueous extract of A. cepa at 40 g/L better preserved omega-3 in fish during smoking and sun drying than the control product. Incorporating the three plant extracts during smoking and sun-drying processes can effectively preserve the PUFAs in fish. Therefore, these plants are viable sources of natural antioxidants in the preservation of fish products.

Yemlere propolis ilavesinin çipura (Sparus aurata L. 1758)’nın yağ asidi profili ve kan parametreleri üzerine etkisi

This study was carried out to investigate the effects of increasing levels of propolis addition as a feed additive in seabream (Sparus aurata) diets on the hematological parameters and the fish fatty acids profile. Seabream with an average weight of 12.04 ± 0.01 g were fed 0 (control), by 1.25, 2.5, 5, 10, 20 g/kg (abbreviated with P1.25; P2.5; P5; P10 and P20 respectively) propolis supplemented diets for 10 weeks. The experiment was conducted in three replications by adding 50 fish to 18 polyester tanks of 400 L. The trial groups were fed twice daily (09:00 and 17:00) by hand to satiation with feed containing 45% protein and 17% lipid. Although the propolis supplementation had no effect on seabream saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA), the polyunsaturated fatty acid (PUFA) contents increased significantly after the addition of 10 g/kg propolis. Therefore, the addition of the propolis to feeds significantly affected the total fatty acid composition of fish (p &lt;0.05). As a result, the propolis supplement improved the quality of seabream fatty acid composition. At the end of the experiment, hematological parameters such as RBC (erythrocyte count in red blood cells), HGB (hemoglobin count in blood) and HCT (erythrocyte and hemoglobin count in blood) in blood samples taken from fish were found to be higher in P20 group than the other groups. There was no significant difference between the experimental groups (p &gt; 0.05). The addition of the propolis to their feed did not have any effect on the hematological parameters of seabream. The results obtained showed that the propolis has the potential to use in seabream feeds.

Fatty acid composition of fish feeds vended in Lagos state, Nigeria

Fatty acid compositions of the lipids extracted from various fish feeds (Eco-float, Blue-crown, Uncle - frances, Triton, Stretting, Crown, Jik, Shaldac, Solace, Coppens, Vital, Local sinking, Local feed, Aqualis and Local floating) vended in Lagos State were determined. These feeds were designated as Feeds A to O respectively. Feed samples were procured from major fish feed markets and fish farms within Lagos metropolis and transported to the laboratory for analysis. Methylation was carried out after oil extraction to convert the fats to their methyl esters and the fatty acids methyl esters (FAME) were separated by gas chromatography. Fatty acids were analysed using a HP Agilent 5890 system gas chromatograph equipped with SP-2330 and a flame ionization detector (FID). Results revealed that the highest values for polyunsaturated fatty acid (PUFA), saturated fatty acid (SFA) and ∑n-3 unsaturated fatty acid (HUFA) were 58.26% in feed F, 38.7% in feed M and 3.59% in feed N respectively while the lowest values for PUFA (19.76%) and SFA (15.53%) were recorded in feeds M and J respectively. The results also showed that, though feed samples were high in monounsaturated fatty acid (MUFA) (55- 22%) and PUFA (58-19%), they were low in n-3 HUFA {eicosapentaenoic acids (EPA, 20:5n-3) and docosahexaenoic acids (DHA, 22:6n-3)} with the values of 0.3-3%. The shortfall in EPA and DHA of these feeds may imply that fish fed these feeds may be nutritionally deficient in these fatty acid compositions. Thus, further manipulation may be needed to improve the value of these feeds in terms of EPA and DHA.&#x0D; Keywords: Fish feeds, n-3 HUFA, n-6 HUFA, Nutritional quality, aquaculture

Interactive effect of dietary fish oil and pyrimidine nucleotide supplementation on the fatty acid composition of juvenile rainbow trout Oncorhynchus mykiss : Enhancement of ARA and DHA contents in the fillet of fish fed‐supplemented diet

The present study investigated interactive effect of different levels of dietary fish oil and pyrimidine nucleotide supplementation on growth and fatty acid composition of juvenile rainbow trout. Six experimental diets were formulated with two different levels of fish oil. High fish oil (HFO) diet contains 120 g/kg fish oil, while low fish oil (LFO) diet contains 40, 60 and 20 g/kg fish, linseed and rapeseed oils respectively. Uridine 5’-monophosphate (UMP) or cytidine 5’-monophosphate (CMP) disodium salt was supplemented onto each diet at 1.5 g/kg respectively. For control diet, UMP and CMP were not supplemented to HFO and LFO diets respectively (HFO-Cont. and LFO-Cont.). Rainbow trout with initial average body weight of 13.5 g were randomly placed into 12 tanks and offered one of the six diets for 12 weeks. Growth, feed utilization and hepatosomatic index (HSI) of fish were not influenced by either fish oil or pyrimidine nucleotide supplementation. This trend was also similar on the crude lipid content in the liver and proximate composition in the muscle and whole fish body. In addition, fatty acid composition in the liver was influenced by fish oil level, but not by pyrimidine nucleotide supplementation. Interestingly, pyrimidine nucleotide supplementation affected 20:4n-6 and 22:6n-3 contents in the muscle of fish. In summary, although dietary UMP and CMP have no positive effect on growth, it affected on the fatty acid composition of fish by increasing muscular 20:4n-6 and 22:6n-3 contents particularly when it is supplemented in low fish oil-based diet.

Comparative study of the fatty acid composition of light/dark mixture musculature of five freshwater fish from the region of Dezful, Iran

Fatty acid composition of fish is one of the key factors for the evaluation of fish nutritional value and it could be different based on fish species, habitat, nutrition and etc. The aim of the present study was to evaluate the fatty acid composition of five commercially important freshwater fish species taken from fisheries sites at Dez River, Iran. The fish samples included Heckel’s Orontes barbell, Luciobarbus pectoralis (Heckel, 1843), Chub, Squalius cephalus (Linnaeus, 1758), Common carp, Cyprinus carpio (Linnaeus, 1758), Brond-snout, Chondrostoma regium (Heckel, 1843) and Longspine scraper, Capoeta trutta (Heckel, 1843). The determination of fatty acid contents of the fish fillets were conducted by means of Gas chromatography. Results showed that Luciobarbus pectoralis fillets had the highest amount of fatty acids (43.49%). Cyprinus carpio had the highest amount of saturated fat (SAF) (29.43%) whereas the Luciobarbus pectoralis fillets had the highest MUFA (Monounsaturated fatty acid) (18.51%). The Squalius cephalus fillets possessed the highest amount of PUFA (polyunsaturated fatty acid) (1.87%). The Chondrostoma regium fillets revealed the highest n-6 (1.1%) while the Squalius cephalus fillets had the highest omega 3 (1.87%). The results of the present study showed that these freshwater fish are good sources of n-3 fatty acids, especially EPA and DHA, and could be considered as a valuable nutritional source.

Zebrafish (Danio rerio) physiological and behavioural responses to insect-based diets: a multidisciplinary approach

Black Soldier Fly (BSF) meal is considered as an alternative, emerging and sustainable ingredient for aquafeed production. However, results on fish physiological responses are still fragmentary and often controversial, while no studies are available on fish behavior in response to these new diets. The present work represents the first comprehensive multidisciplinary study aimed to investigate zebrafish physiological and behavioural responses to BSF-based diets. Five experimental diets characterized by increasing inclusion levels (0, 25, 50, 75 and 100% respect to fish meal) of full fat BSF prepupae meal were tested during a 2-months feeding trial. Prepupae were cultured on coffee silverskin growth substrate enriched with a 10% Schizochytrium sp. to improve insects’ fatty acids profile. The responses of zebrafish were assayed through biometric, histological, gas chromatographic, microbiological, spectroscopic, molecular and behavioural analyses. Results evidenced that BSF-based diets affected fish fatty acid composition, while behavioural tests did not show differences among groups. Specifically, a 50% BSF inclusion level diet represented the best compromise between ingredient sustainability and proper fish growth and welfare. Fish fed with higher BSF inclusions (75 and 100%) showed hepatic steatosis, microbiota modification, higher lipid content, fatty acid modification and higher expression of immune response markers.

The Impact of Water and Ethanolic Extracts of Propolis on Fatty Acid Changes of Sardine Fillets

The polyunsaturated fatty acids (PUFA) of lipids in muscle of sardine were known as unstable to oxidation. Propolis is a natural compounds produced by honey bees from substances collected from parts of plants, buds, and exudates. Nowadays, the particular attention has been attributed to propolis underlying their antioxidant properties due to the presence of the flavonoids, phenolic acids, and ethers. The impact of water and ethanolic extract of propolis at doses of 0.4 and 0.8% on fatty acid changes of vacuum packaged sardine fillets were investigated during chill storage. The main fatty acids in sardine fillets were palmitic acid (C16:0), palmitoleic acid (C16:1), myristic acid (C14:0), eicosapentaenoic acid (EPA, C20:5n3) and docosahexaenoic acid (DHA, C22:6 n3), respectively. There was no significant differences in EPA and DHA between control and treated groups during storage apart from 4 and 11th day. Initial n6/n3 ratio in sardine fillet was 0.17. Group treated with 0.4 propolis ethanolic extract comprised lower n6/n3 ratio at 4, 11 and 13th days than that of other groups. Although the effects of propolis extracts on fatty acid composition of fish were variable, application of propolis ethanolic and water extracts on fish fillets at doses of 0.8% had a positive impact due to lead a better oxidative stability of PUFA content.

Comparison of Fatty Acid Contents in Major Lipid Classes of Seven Salmonid Species from Siberian Arctic Lakes.

Long-chain omega-3 polyunsaturated fatty acids (LC-PUFA) essential for human nutrition are mostly obtained from wild-caught fish. To sustain the LC-PUFA supply from natural populations, one needs to know how environmental and intrinsic factors affect fish fatty acid (FA) profiles and contents. We studied seven Salmoniformes species from two arctic lakes. We aimed to estimate differences in the FA composition of total lipids and two major lipid classes, polar lipids (PL) and triacylglycerols (TAG), among the species and to evaluate LC-PUFA contents corresponding to PL and TAG in muscles. Fatty acid profiles of PL and TAG in all species were characterized by the prevalence of omega-3 LC-PUFA and C16-C18 monoenoic FA, respectively. Fish with similar feeding spectra were identified similarly in multivariate analyses of total lipids, TAG and PL, due to differences in levels of mostly the same FA. Thus, the suitability of both TAG and total lipids for the identification of the feeding spectra of fish was confirmed. All species had similar content of LC-PUFA esterified as PL, 1.9–3.5 mg g−1, while the content of the TAG form strongly varied, from 0.9 to 9.8 mg g−1. The LC-PUFA-rich fish species accumulated these valuable compounds predominately in the TAG form.

Influence of dietary linseed oil as substitution of fish oil on whole fish fatty acid composition, lipid metabolism and oxidative status of juvenile Manchurian trout, Brachymystax lenok

In this study, juvenile Manchurian trout, Brachymystax lenok (initial weight: 6.43 ± 0.02 g, mean ± SE) were received for nine weeks with five types of diets prepared by gradually replacing the proportion of fish oil (FO) with linseed oil (LO) from 0% (LO0) to 25% (LO25), 50% (LO50), 75% (LO75), and 100% (LO100). The eicosapentaenoic (EPA) and docosahexaenoic (DHA) composition decreased with increasing inclusion level of LO (P < 0.05). With increasing LO inclusion level, triglyceride (TAG) content of serum increased significantly, however, there was a decrease in high-density lipoprotein cholesterol (HDL) (P < 0.05). LO substitution of FO up-regulated the gene expression level of lipid metabolism-related genes Fatty Acid Desaturases 6 (FAD6), Acetyl-Coa Carboxylase (ACCα), Sterol Regulatory Element Binding Protein 1 (SREBP-1), and Sterol O- Acyl Transferase 2 (SOAT2), and down-regulated the gene expression level of Peroxisome Proliferator-Activated Receptor a (PPARα) (P < 0.05). The SOD activities of both serum and liver in LO100 were significantly lower than in LO25 (P < 0.05). The CAT activity of the liver in LO100 was significantly lower than in LO0 and LO25 (P < 0.05). This study indicates that the Manchurian trout may have the ability to synthesize LC-PUFAs from ALA, and an appropriate LO in substitution of FO (<75%) could improve both the lipid metabolism and the oxidation resistance.

Insect meal based diets for clownfish: Biometric, histological, spectroscopic, biochemical and molecular implications

Basic nutrition for tropical fish is undeniably lacking, mainly due to the concentration of research efforts on and funding for food fish species. However, as the marine ornamental aquaculture industry continues to grow and expand, it is now essential to direct nutritional research to mitigate the current lack of information related to feeds specifically formulated for ornamental fish. Due to a minimal environmental impact, compared to most conventional feed commodities, insects deserve a growing attention as candidate ingredient for aquafeeds and Hermetia illucens, the black soldier fly, is presently one of the most promising insect species. The aim of the present study was to formulate new insect based diets and to evaluate, through a multidisciplinary approach including morphological, biochemical, spectroscopic and molecular analysis, the major biological responses of Amphiprion ocellaris juveniles fed on these diets over a 106 days experimental period. Biometry did not reveal differences in survival and growth; fish fatty acid composition was influenced by the diets. Real-Time PCR analyses on genes involved in fish growth (igf1, igf2 and mstn), lipid metabolism (pparα and pparβ) and stress response (gr and hsp70), did not show significant differences among groups. Histology showed a normal intestinal mucosa and liver parenchyma in all experimental groups. Lower amounts of lipids and proteins, together with a higher amount of glycogen, were detected by FTIR in the liver of clownfish fed on diets including higher insect meal amounts.

Effect of season and trophic level on fatty acid composition and content of four commercial fish species from Krasnoyarsk Reservoir (Siberia, Russia)

Two groups of factors, phylogenetic and ecological, are presently regarded as controlling fatty acid composition of fish, including essential eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. Environmental effects, e.g., trophic position, temperature and/or seasonality, were previously studied using sums of fatty acids or only their level data. We tested the hypothesis that differences in trophic levels of piscivorous (pike and perch) and omnivorous (roach and bream) fish from a mesotrophic reservoir allow discriminating levels and contents of individual fatty acids, especially EPA and DHA. The more established measurements, i.e., stomach contents and carbon and nitrogen stable isotopes in fish muscles, were also carried out to provide linkages between the different ecological tracers, fatty acids versus stable isotopes, and matching the methods for long-term food sources (fatty acids and stable isotopes) and recent foraging (stomach content analysis). We also studied a putative influence of seasonality. Similar to other studies, there were seasonal changes in fatty acid composition and contents of two fish, perch and roach, due to direct and indirect effects of water temperature. Meanwhile, the piscivorous and omnivorous species captured in the same month, were explicitly differentiated on a base of stable isotopes and fatty acids. Significantly higher percentages and contents of DHA in piscivorous fish, perch and pike, relatively to those in roach and bream, likely indicated a higher trophic transfer efficiency for this essential fatty acid. All the fishes have commercial importance for regional fishery and are harvested from the studied reservoir for human nutrition. Regarding content of EPA+DHA (mgg−1 fish) as the indicator of nutritive value for humans, pike had the highest nutritive value, roach and perch had intermediate overlapped values, and bream was of the least benefit.

The Effects of a Transition Diet on the Smoltification of Chinook Salmon

AbstractTransition diets, often supplemented with salt and other additives, have been used to prepare Pacific salmon Oncorhynchus spp. being moved directly from freshwater to saltwater net pens for aquaculture production. However, the use of transition diets to prepare hatchery‐reared salmon released into freshwater prior to out‐migration to the ocean has shown mixed results. We compared the physiological (size, condition factor, Na+,K+‐ATPase [NKA] enzyme activity, survival during a saltwater challenge) and nutritional (proximate composition, fatty acid profile) condition of juvenile Chinook Salmon O. tshawytscha that were fed either a standard hatchery feed or a commercially available transition diet for the final 6 weeks of hatchery rearing to determine whether the transition diet altered smolt condition. At release, NKA activity of fish fed the transition diet was higher than that of fish fed the control diet, though survival during a saltwater challenge was similar between groups. Differences were seen in the proximate composition of the fish, with increased total body moisture and decreased lipid in the fish fed the transition diet relative to fish fed the control diet. Whole‐body fatty acid composition of fish was similar to the fatty acid composition of the feeds in both groups, though some key whole‐body fatty acids did not follow this trend. Palmitic acid (16:0), linoleic acid (18:2[n‐6]), eicosapentaenoic acid (20:5[n‐3]), and docosahexaenoic acid (22:6[n‐3]) varied between prefeeding trial samples and fish fed the two diets. Further research is required to determine whether the physiological changes that occurred are related to smoltification or the maintenance of osmotic balance while fish are fed additional salt.

Unrefined Peanut Oil as a Lipid Source in Diets for Juveniles of Two‐banded Seabream Diplodus vulgaris

AbstractA feeding study with Two‐banded Seabream Diplodus vulgaris was conducted to determine the effects of replacement of fish oil (FO) by unrefined peanut oil (PO) on growth performance, feed utilization, body composition, fatty acid composition, and serum biochemical and hematological variables. Three isonitrogenous (35.8%) and isoenergetic (21.15 kJ/g) diets were formulated by replacing dietary FO with PO at levels of level 0% (PO0), 50% (PO50), or 100% (PO100). Fish were fed twice a day until satiation for an experimental period of 8 weeks. The best growth performance was observed in fish fed with the PO0 and PO50 diets. A significant increase was observed in hematocrit and mean corpuscular volume levels of fish fed with PO50 diet compared with the other groups. Hemoglobin, mean corpuscular hemoglobin, total protein, albumin, and globulin were not affected by dietary PO treatment and did not differ among experimental groups. The glucose level was highest in the PO100 group. Triglyceride and cholesterol levels were lower in fish fed diets with PO inclusions than in those fed the control diet. The fatty acid composition of fish was significantly affected by the experimental diets. Glutamic oxaloacetic transaminase, glutamic pyruvictransaminase, lactate dehydrogenase, and alkaline phosphatase were not affected by dietary PO treatment. The n‐3:n‐6 ratio in fish fed the PO0 diet was also higher than in fish fed the PO‐supplemented diets. The results of the present study showed that FO could be substituted by PO up to 50% in Two‐banded Seabream diets without any negative effect on growth performance or serum biochemical and hematological features.

Molecular cloning and nutritional regulation of putative ∆6 desaturase mRNA from striped catfish (Pangasianodon hypophthalmus)

Here we report the full-length cDNA cloning and nutritional regulation of a putative Δ6 fatty acyl desaturase (Δ6 fads) gene from striped catfish, Pangasianodon hypophthalmus. The 5′ and 3′ RACE analysis revealed a cDNA sequence of 1896 base pairs (bp) comprising a 5′ UTR of 49bp, 3′ UTR of 509bp and an open reading frame (ORF) of 1338bp specifying a protein of 445 amino acids. Bioinformatics analysis showed that the deduced peptide sequence included all the characteristic features of microsomal fatty acyl desaturases, including N-terminal cytochrome b5 domain containing the haem binding motif H-P-G-G, fatty acyl (FA) desaturase domain, three histidine boxes and transmembrane regions. P. hypophthalmus ∆6 desaturase peptide sequence shares high similarity with Pangasius larnaudii (95%) and Clarias macrocephalus (90%). The predicted secondary and tertiary protein structures revealed that desaturase protein contains mostly α-helix followed by random coils and strands. Tissue distribution analysis showed that Δ6 fads is mainly expressed in brain followed by liver, heart, gill and muscle. Since α-linolenic acid is a substrate for the Δ6 FADS enzyme, various concentrations of this fatty acid (0.5, 1, 1.5 and 2gkg−1) were administered to experimental fish through feed to find out its effect on the expression of Δ6 fads. Results showed that the liver Δ6 fads gene expression is up-regulated in fish fed with experimental diets (p<0.05). Statement of relevanceThe fatty acid composition of fish depends on both dietary fatty acid input and endogenous HUFA biosynthesis capacity. Fatty acyl desaturases (fads) introduce double bonds in selected positions of the acyl chains. Particularly, Δ6 FADS are the first enzymes involved in the biosynthesis of long-chain HUFA from the C18 n-3 and n-6 precursors, which is a rate limiting step. The extent to which fish can desaturate/elongate C18 FAs to HUFAs varies with species. Hence it is important to study the relationships between LC-PUFA biosynthesis pathways and the habitat and feeding habit of fish species, which will provide the basis for understanding the regulatory mechanisms controlling LC-PUFA biosynthesis pathways. The present study reports the full-length cDNA cloning, tissue distribution and nutritional regulation of Δ6 fads-like gene from freshwater catfish, P. hypophthalmus. This is the first report on cloning and expression analysis of Δ6 fads-like gene from any freshwater catfish.

An evaluation of the complete replacement of both fishmeal and fish oil in diets for juvenile Asian seabass, Lates calcarifer

An experiment was conducted to examine the potential for the complete replacement of fishmeal (FM) and fish oil (FO) in diets for barramundi, Lates calcarifer. A series of diets were formulated to the same digestible protein and energy specifications, but which were designed with FM inclusion levels at 300, 200, 100 or 0g/kg and FO at 100%, 30%, 15% or 0% of the added oil in the diets (4×4 factorial design). Ricebran oil was the alternative oil used in the growth study, while soybean meal and poultry meal were the main alternative protein sources used. For the growth study, fish of an initial weight of 154.4±1.1g were randomly allocated across 48 tanks (three replicates per treatment). After eight weeks, the average weight gain across all treatments was 187.7±2.3g/fish and feed conversion across all treatments averaged 1.04±0.01 feed/gain. A significant effect of FM on both feed intake and weight gain was observed, and this was observed as early as within the first few weeks, but no similar such effect was observed with FO. No effects were observed on protein deposition efficiency, though both lipid and energy deposition efficiencies were affected by FM level. The reduction in FO had a notable effect on the fatty acid composition of the diets and subsequently the fish fatty acid composition. Expression of key LC-PUFA metabolism genes in the liver of the fish was influenced by both FM and FO levels, but was only significant at the extremes of the treatment ranges. The results from this study demonstrate that there is clear potential to replace almost all the FM content of barramundi diets without loss of fish performance, up to and including diets with as little as 100g/kg fishmeal. Replacement of fish oil was more successful with the ability to completely replace all FO demonstrated at all but the lowest inclusion levels of FM. These results clearly demonstrate that the near complete replacement of both FM and FO in barramundi diets is a technical reality.

The fatty acid composition of fish and shellfish in Lake Biwa

The fatty acid composition of fish and shellfish in Lake Biwa

Differentiating the wild or farmed origin ofMediterranean fish: a review of tools for sea bream and sea bass

AbstractBased on the fact that farmed fish experience different environments, stocking densities and feeding regimes compared with wild fish, several techniques have been developed to discriminate the wild or farmed origin of fish. These techniques quantify differences between genetics, chemical characteristics, fatty acid compositions, trace elements, pollutants, stable isotopes, morphology and organoleptic characteristics. Gilthead sea bream and European sea bass are the most important marine fish in Mediterranean aquaculture and are highly appreciated by commercial and recreational fisheries. A total of 60 studies that used techniques to discriminate farmed from wild fish for sea bream and sea bass form the basis of this review. The most common technique used differences in the lipid and fatty acid composition of fish. Many of these studies dealt with food science and product quality, rather than tracing escapees. A wide range of identification tools is useful in determining the correct origin of captures and proper labelling of marketed fish. External appearance and morphometry are useful for rapid assessments and can be achieved with high accuracy and little cost, especially for sea bream. This makes these methods suitable for detecting large and recent escape events, applicable in fisheries studies, and for ensuring that wild and farmed fish are separated in the marketplace. Techniques using differences in chemical or genetic composition are more useful for environmental monitoring, as they have higher accuracy and can detect escapees long after the escape incident. Regulatory bodies should legislate protocols that describe the technique(s) that must be applied in specific circumstances.

Partial replacement of fish meal with &lt;em&gt;Azolla&lt;/em&gt; meal in diets for Nile tilapia (&lt;em&gt;Oreochromis niloticus&lt;/em&gt; L.) affects growth and whole body fatty acid composition

The replacement of fishmeal (FM) with Azolla meal (AM) in diets on growth and fatty acid in Nile tilapia, Oreochromis niloticus (initial mean weight: 16.4 g) was studied. Fish were fed with six isonitrogenous (29.2% CP) and isoenergetic (16.9 kJ.g-1) diets containing 0%, 10%, 20%, 30%, 40% and 50% AM respectively, as partial FM substitute. Diet A0 acted as a control. The final weight (51.0-88.3 g), the weight gain (210.8-438.3%) and the SGR (1.3-1.9%day-1) decreased when AM level higher than 10% in diets (P &lt; 0.05). The FCR (1.44 to 2.35) significantly increased when AM level exceeded 20% (P &lt; 0.05). The protein efficiency ratio and the apparent net protein utilization decreased consequently. The fatty acids in the whole fish were significantly influenced by the diets. The replacement of FM by AM produced fish with lower (n-3) highly unsaturated fatty acids mainly docosahexaenoic acid, and higher arachidonic acid (P &lt; 0.05). The n-3/n-6 fatty acid ratio ranged from 0.08 to 0.17, and was lower in fish fed A40 and A50 (P &lt; 0.05). The findings suggest that high AM in diets affects Nile tilapia growth and the fern could be incorporated in diets up to 30% without any adverse effect on fish fatty acid composition. However, alternative additional source of lipid must be used to improve the quality of fish fed AM-diets.Keywords: Azolla, Fish meal replacement, Growth, Fatty acids, Oreochromis niloticus, bioconversion

Growth, body chemical composition and trypsin activity of South American catfish, surubim (Pseudoplatystomasp.) juveniles fed different dietary protein and lipid levels

To evaluate protein and lipid requirement of South American catfish surubim (Pseudoplatystoma sp.) juveniles, nine semi-purified diets containing three levels of protein (40%, 45% and 50%) and three levels of lipid (12%, 16% and 20%) were tested. After 8-week feeding trial, body weight increase averaged 2124.3 ± 295.7%. Growth performance was significantly affected by dietary level of protein (P < 0.05). At the 40% protein level, increasing level of dietary lipid had a positive effect on final individual mean weight (protein sparing effect). Whole body protein and moisture contents were affected by the dietary level of lipid (P < 0.05). Whole body lipid content positively correlated with the level of dietary lipid (P < 0.05). Cannibalism related mortality was observed despite rearing fish in 24 h dark. Fatty acid composition of fish was affected by the dietary lipid level (P < 0.05). Polyunsaturated fatty acids increased with the increasing level of dietary lipid while saturated fatty acids and monounsaturated fatty acids decreased. Trypsin activity in the digestive tract of surubim was influenced by dietary levels of protein and lipid (P < 0.05). Our preliminary results suggest that the optimum protein/lipid ratio might be close to 45/16% for surubim juveniles.

A Review on Fish Lipid: Composition and Changes During Cooking Methods

Fish lipids are known to be beneficial for human health since they are rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). This benefit can be affected by some processing or cooking methods. The effects of different cooking methods on lipid content and fatty acid composition of different fish species have been previously studied. In this article, the fish lipid characteristics and their changes during different cooking methods were reviewed. The fat content and fatty acid composition of fish vary according to the species, season, and environmental conditions. The fish lipid characteristics also change during different cooking processes. Frying generally gives higher changes in the fish lipid composition than other cooking methods. For example, frying results in higher losses of DHA and EPA (compared to other cooking methods). Further, the lipid changes occurring during frying depend on the fat content of the fish, the frying oil composition, and the type of frying technology.