Problem statement: Only limited information exists on nutrients in salmonoids meat in Bulgaria, which may to be different and vary to a greater extent than the nutrient composition of other fish items. The present paper is aimed to determine the proximate composition, macro and trace elements of Atlantic salmon`s meat. These data could be helpful in judging the value of nutrient composition data as a base for dietary recommendations. Organisms: 12 species of Atlantic salmon (Salmo salar). Approach: The aim of this study was to determine the proximate composition and levels of iron, potassium, sodium, calcium, phosphorus, magnesium, copper, selenium and zinc in Atlantic salmon cultivated for the first time in Bulgaria. The content of protein, fat and ash and concentrations of iron, potassium, sodium, calcium, phosphorus, magnesium, copper, selenium and zinc were determined by automatic systems and electro thermal atomic absorption spectrometry (ETAAS) after microwave digestion. Mean values and their respective coefficients of variation were calculated from the measured concentrations. Conclusion: In order to provide an accurate overview and to be able to calculate reliable dietary intakes, it is important to know the fish composition data.

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The prolonged starvation has many effects on the physiological and morphological processes in fish and interferes them with the ability to absorb nutrients and caloric intake. The aim of present study was to investigate the effect of long-term starvation and posterior dietary administration of commercial synbiotic consisting fructoligosaccharide (FOS) which used in combination with Enterococcus, Lactobacillus, Bifidobacterium and Lactococcus spp. for evaluation on some blood biochemical parameters and histological characteristics of common carp liver. Experimental fish after 5 months starvation period were subjected to the following feeding protocols: continuous starvation until 60 day (ST), re-feeding (FS) with dry composed diet (Aqua 1032 Swim) and refeeding with composed diet and synbiotic (FSS) for the following 60 days. Blood samples were used for analysis of the following plasma parameters: total protein, albumin, globulin, urea, creatinine, cholesterol, AST, ALT, glucose and serum for thyroid hormones. Histology analyses were performed on the carp liver samples. During the experimental period, fasting and refeeding were influenced significant on studied biochemical parameters, except glucose and urea. Also, the statistically largest (P <0.001) difference was observed in albumin and cholesterol values after refeeding. Our results reveal the changes in values of biochemical parameters during long-term starvation and refeeding with synbiotic and indicate signs of structural alterations of the liver in common carp.

Abstract. The rainbow trout (Oncorhynchus mykiss), an important species in Bulgarian aquaculture, is farmed in different production systems as raceways, net cages etc. The aim of the present study was to evaluate the effect of two different rearing systems on fish production, survival rate, meat chemical, mineral composition and farming economic efficiency of culticated rainbow trout (Oncorhynchus mykiss). The information from a survey on fish production and economic efficiency traits was collected from two national rainbow trout farms using the two commonest fish farming systems: in raceways, Happy Fish Ltd fish farm and in net cages, Forest Group Ltd fish farm. The average individual weight gain (g), total weight gain (kg), feed conversion ratio, production costs of 1 kg fish and the economic efficiency coefficients were determined for the two studied fish farms. The final live weight of rainbow trout in net cages was 0.30 kg vs 0.35 kg in raceways. The average individual weight gain was higher in raceways farming system (0.30 kg) than in net cages farm (0.26 kg). The mortality rate of fish in raceways was considerably lower: only 1% as compared to that in net cages (4%). The feed conversion ratio at the end of the experiment showed identical values for trout in both farms 1.01. The meat water content of fish reared in raceways and net cages was 77.46±0.65% and 74.52±0.52% respectively (P≤0.01).The protein content of fish meat was higher in fish farmed in net cages 18.84±0.29% as compared to fish cultivated in raceways 17.60±0.49% (P 0.05). Meat fat content of rainbow trout, reared in the net cage system was also considerably higher (5.26±0.30%) than the respective parameter in fish farmed in ponds (3.60±0.15%) (P≤0.001). The content of Ca and P was higher in rainbow trouts reared in raceways ( IntroductionThe farming of fish in raceways allows a more accurate control on growth performance and death rate as the trouts could be observed and a timely reaction is possible (Tidwell, 2012). The The aquaculture is dedicated to production of high-quality food different raceways depends on the water available in the water with optimum price. Therefore, the best pathway for achievement of source, the relief etc. Their capacity is influenced on several factors: these two principal tasks of aquaculture should be sought. The flow rate, production volume, water exchange, temperature, oxygen dietetic properties of fish as a foodstuff are determined from the content, water pH, species and size of the hydrobiont, feeding composition of fish meat. The differences in its chemical content regimen, waste accumulation rate. For calculation of raceways depend on various factors as age, the season of catch, capacitie some authors (Hinshaw, 2000; Hinshaw et al., 2004) environmental conditions, feeding and farming technology recommend using the level of water flow rate and fish stocking (Hadzhinikolova and Atanasova, 2007). The chemical composition density. Fish farming in net cages offers several advantages of fish reared in farms co...

The thyroid hormones (THs) play an important role in the regulation of the rate of metabolism, affect the growth and function of different systems in the organism. The aim of this study was to assess serum concentration of total triiodothyronine (T3), total thyroxine (T4) as well as T3/T4 ratio in serum from healthy fresh water fish from Salmonidae, Acipenseridae, Cyprinidae, and Clariidae families to determine species-specific reference intervals. Mean concentrations of T3 and T4 levels varied significantly among fish. Finally, the test results show clear differences in the serum concentration of the T3 and T4 and give new insight into the thyroid hormones reference values in some commercial fresh water fish species.