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The effect of cobalt-chloride on the production parameters and homogenity of barramundi (Lates calcarifer) larvae
Published February 10, 2013

...5); font-variant-ligatures: normal; font-variant-caps: normal; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">Barramundi (Lates calcarifer) is a predatory fish species native in Southeast Asia and Australia. Based on the geothermal potentiality of Hungary the high market potential warm-water fish barramundi can be produced economically. Living nourishment organisms such as Artemia nauplii play an essential role in the larval rearing of barrramundi. However, zooplanktons in natural aquatic enviroments contain minerals in a higher concentration than the usually fed newly hatched Artemia. Therefore the goal of recent study was to investigate the effect of cobaltchloride on the larval growth and survival of barramundi when fed individually and combined with Zn and Mn supplemented Artemia.

In our experiment a 24 hours period was used for the enrichment of newly hatched Artemia nauplii with cobalt chloride in itself, as well as in combination with zinc sulphate and manganese chloride. A total of 1900 barramundi larvae from 15–30 day post hatching were fed with supplemented Artemia in 9 groups of treatments in duplicate. The growth performance and elemental concentration of 40 larvae from each group was determined. All the groups produced significantly improved growth compared to the control (p<0.05). The lower concentration of individual Co supplementation resulted in a higher growth performance while the opposite dose relation occured when combined the Co with Mn. Cobalt had a significant negative effect on the Mn uptake of the larvae – significantly higher Mn accumulation compared to the control group was only observed when Mn was fed in itself (p<0.05). In case of Co-Zn-1 and Co-Zn-2 treatments significantly higher Zn concentration was measured than in the others (p<0.05).

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The effects of the nanoselenium supplementation to the production parameters and the selenium retention of the red drum (Sciaenops ocellatus)
Published March 20, 2014

The selenium is an essential trace element with antioxidant effect, constituent of many enzymes, natural component of the body of the animals. The addition to the fish feed as micro element supplementation is generally accepted. Numerous animal experiments veryfied, that the antioxidant effect of the nanoselenium is higher than other selenium f...orms. But no much information is available of the usuage at fish.

In the experiment were investigated the effects of the nanoselenium supplementation of a commercial fish feed were investigated to the production parameters and the body tissue composition. The correlation between the accumulated selenium content of the body and the treatment, and the feed conversation was also statistically analyzed beside the production parameters. Furthermore we were curious, if can be toxic the nanoselenium in higher doses.

The experimental stock was placed into 12 plastic tanks (each 70 l water vol.) in a recirculation system for larval rearing. The salinity and the water temperature was constant during the 8 week long experiment. The feeding was ad libitum, 4 times a day. Beside the control five (1, 1.5, 2.5, 5.5, 10.5 mg Se kg-1) duplicated treatment were set.

According to the results, from the production parameters only at the value of FCR and the survival was found significant difference (p<0.05) between the groups. However strong correlation (r=0.752–0.780, p<0.01) was determined between the treatment and the accumulated selenium levels. To analyzed the free fatty acid contentof the fish, we realized, that the selenium uptake significanly enhanced this level at all treatments. The greatest change was found in case of the type n-3 fatty acids.

Established by the results, the higher intake than 0.5 mg Se kg-1 was not changed significantly the production parameters, nevertheless to increase the selenium content of commercial feeds to 1.5 mg Se kg-1 could be rewarding on the rearing of red drum.

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The use of essential trace elements in the juvenile rearing of barramundi (Lates calcarifer
Published March 20, 2014

Barramundi (Lates calcarifer L.) is a predatory fish species native in Southeast Asia and Australia. Based on the geothermal potentiality of Hungary the warm-water fish can be reared successfully. Zooplankton in the wild contains minerals in a higher concentration than the usually fed newly hatched Artemia nauplii, therefore essential trace ele...ments, such as cobalt, zinc and manganese play an important role in the larviculture of barramundi. Cobalt is vital in trace amount for many living functions of vertebrates, however, lower number of papers are available considering the nutritional aspects. Nevertheless. improved growth performance was observed in cases of some fish species when diet was supplemented with CoCl2. Zinc and manganese are also vital for optimal growth and accordingly are investigated and applied diet supplements in aquaculture.

The main aim of the recent study is to investigate the effects of cobalt, manganese and zinc on the growth performance and homogeneity of fish when a commercially available dry diet is supplemented with trace elements individually and in combined treatments. A total of 6 treatments were set in a randomized blocked design where the concentrations of the applied elements were 50 mg kg-1 for CoCl2, for ZnSO4 and for MnCl2 individually, as well as for CoCl2 along with ZnSO4 and for CoCl2 along with MnCl2 in combination. Although the production parameters of larval barramundi were positively affected by the addition of trace elements when the retention of minerals occurred through nourishment living organisms, statistically no differences were found between the treatments considering the growth performance of barramundi juveniles either when dry feed was supplemented with cobalt, manganese or zinc (p>0.05). While the use of cobalt and manganese in combined treatments produced a less uniform larvae in size and as a consequence of increased heterogeneity, survival was significantly reduced by the cannibalism, the sizes distribution of barramundi juveniles wasn’t affected by the dry diet supplementation of these elements.

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Practical experiences of a designing and operating a pilot aquaponic system
Published March 20, 2014

Aquaponics is the combination of fish farming (aquaculture) and the soilless cultivation of plants (hydroponics). The aquaponics system is an artificial, recirculating ecosystem, in which bacterial processes convert the waste materials in the water used for fish rearing into plant nutrients, and therefore with the generated heat it is suitable ...for culturing economically valuable plants, and thus it mitigates the nutrient laden and quantity of the intensive fish producing systems’ effluent water.

The primary goal of our 12 separate unit’s aquaponics system was to gain experience. We would like to find the right plant species, which are fit for that medium, and their crop can be sold. Besides the plants, our attention focused on the fish. Two fish species were included in the experiments, the common carp and barramundi. It was difficult to create them a perfect living space, besides a constantly changing conditions temperature. Apart the above mentioned we had a problem with the number of individuals per tank, the deformity of the fish body and the too high volume of pH (we registered continuous values above 8.4). We get by carps 4.7 grams of weight gain during 15 weeks, because of the bad conditions.

The main problems at the plants are caused by aphesis and protection against sunburn. Even so we have got the multiples of field yields for each plant species. At salad has grown twice of field yields, tomatoes one and half, kohlrabi than 3.5 times more. The causes of multiple yields are the continuous balanced water and the nutrient uptake of plants. Each plant species fit for cultivating in aquaponics and their crops are delicious, chemical -free, safe and marketable. The plants should be more concentrated. After the experiment, it has been determinated that the carp is suitable for aquaponics, but greater weight gain could be achieved with optimal selection of size of rearing units.

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The effects of bioactive feed additives for the production parameters of common carp (Cyprinus carpio) fingerlings in intensive recirculating system
Published March 24, 2015

For the appropriate quantity and quality of fish meat the pond farmers need to use up to date nutrition and feeding technologies. Recently the intensification of the carp production is stepping up with the availability the proper quality of the artificial feeds. The using of different feed additives make a better feed conservation ratio, faster... growing rates and more uniform stocks.

In our experiment what is made with common carp (duration of the experiment was 8 weeks long) we compared two different kinds of feed additives in different doses. One of them contains only natural mineral elements and the other additive is a natural origin probiotics. Both additives were used in the quantity of 0.5, 1 and 2% of the total feed. By the result of the 8 weeks experiment it could be said, that the using of the humic acid based mineral elements feed additive. Makes a better FCR comparing with the control stock, but was not as good as the using of the probiotics. At the humic acid treatments the more doses, the better FCR value, but at the probiotics it wasn’t true. The 0.5% probiotic treatment gave the best result. It is concluded that the using of the probiotic feed additives always gave a better performance of the fishes (average weight, biomass, FCR) than the humic acid treatments. The using of the feed additives hasn’t got an influence for the survival rate of the carps.

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Effect of different weaning time on the growth and survival ofCommon carp (Cyprinus carpio L.) larvae
Published December 28, 2018

Within our experiment, we studied the combined effect of live food application and feed training on the production parameters of carp larvae. In addition, we examined whether there is a difference in the growth rate and survival rate of the specimens of Szeged mirror landrace reared in similar stocking density but with different treatments.


Specimens of Szeged mirror landrace from induced propagation were placed into 12 pieces of 40-liter aquaria. For the 4 different treatments, (K, A3, A6, A9), live food (Artemia salina) was fed, as well as feed training was applied.

We also sought to find an answer as to how our feeding and rearing conditions can affect the production parameters of common carp fries and what impact these conditions may have on their survival rates. At the end of the 2-week experiment we determined the individual weight gain of the carp fries, their survival rate and the biomass growth. The purpose of the study is to examine the optimum timing of shifting from live food to feed for carp larvae.

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Influence of 17-alpha methyl testosterone on the production parameters of common carp (Cyprinus carpio L.) fry
Published December 28, 2018

During our research we aimed at finding an answer as to what extent the different concentrations of 17-alpha methyl testosterone incorporated in the diet of common carp fries can influence the production parameters of the species, as well as how efficient their sexreversal can be with the use of this method. To this end, an aquarium experiment ...was conducted in the course of which four different hormone treatments were set and monitored. The fish feed was enriched with 17-alpha methyl testosterone in 50 ppm, 75 ppm, 100 ppm, 500 ppm dosages.

The obtained figures revealed that the hormone treatments had no influence on the production parameters and conservation of the common carp fries. Further on, our team is to determine the sex of the fish through the examination of gonads during autopsy when they reach the 500 g average weight.

Furthermore, a male specific test method which was supposed to be of great help in our attempt to select the sex-reversed specimens in the subsequent processes was also put to the trial. During the experiment the DNA-isolation of different sample types (muscle tissue, fin, mucus) of common carp with identified sex was successfully carried out. The extracted PCR product was examined with agarose gel. Our results indicated that the ccmf2 marker was applicable, however, the obtained figures were not reliable.

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Effects of bioactive plant extracts on immune-related gene expression of common carp (Cyprinus carpio)
Published December 1, 2020

 In recent years, intensive fish farming has led to an outbreak of several diseases, and the health status of fish can affect the economy of aquaculture. Since fish health and intestinal health are in correlation, it may also have an impact on immunity. Accordingly, many natural feed additives are being used to im...prove immune functions. In our study, carotenoids, oligosaccharides, and anthocyanins were applied at 1 m/m% in feed to investigate their effects on cytokines, such as interleukin-1β (IL-1β), interleukin-8 (IL-8), tumor necrosis factor-α (TNF-α), and interferon regulatory factor-1 (IRF-1) in spleen and mid-intestine of 6 months old carp. Gene expression analysis was carried out to examine IL-1β, IL-8, TNF-α, and IRF-1 mRNA levels in fish spleen and mid-intestine. The gene expression level of pro-inflammatory IL-1β decreased in the mid-intestine of carotenoid-fed carp compared to anthocyanin supplemented group, but the effects of the bioactive plant extracts were not observed on the examined cytokines compared to control fish.

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Comparison of the technological background of aquaponic systems
Published May 20, 2020

Aquaponics is the combined culture of fish and plants in recirculating aquaculture systems, an ecologically sustainable horticultural production technique with long traditions.

The objective of this study is to compare flood-and- drain, and the water crossflow system and examine the differences in the water quality, fish yi...eld and plant growth parameters for Common carp (Cyprinus carpio) and basil (Ocimum basilicum). During the study, water quality parameters of two treatments were compared in temperatures, pH, EC and NON were significantly different (p <0.05). Leaf area of the basil plants grew to an average of 20.37 cm2 (± 9.02 cm2). The plants’ biomass production was significantly different (p< 0.05) in the two systems. The biomass production showed lower yield, 458.22 g (± 214.59 g) in the constant flow system that in the flood- and- drain system 692.9 g (± 175.82 g). Fish Growth parameters were better in constant flow system (FCR 5.48 g/g ± 0.19). However, the specific growth rate (SGR) demonstrated that fish grew faster in flood- and- drain system 1.38 %/day (± 0.29).

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Comparision of growth of mature all-female and mixed-sex Common carp (Cyprinus carpio L.) stocks in RAS
Published May 20, 2020

The common carp (Cyprinus carpio L.) is the most important fish species in Hungary, it is more than 70% of the total Hungarian fish production. The common carp production is important not only just in Hungary but in Middle-East Europe, as well as Southeast Asia. Majority of the production comes from fishpond culture. If the production secto...r wants to meet the increasing customer demands, there is need to intensify research on the intensive fish production opportunities for example all-female common carp technologies. The all-female technology is one of a genom-manipulation technology. Its production showed better growth rate than mixed-sex population in pond culture. Our experiment combined the recirculation aquaculture system (RAS) and the all-female common carp stocks intensification technologies. The reason for the experiment, is that there are no result about the growth of all-female common carp growth in RAS.

The experiment used the „Tatai grey scale type” common carp stocks. We propagated two all-female stocks (T2 and T3) and a control group (TK). Due to technological characteristics of RAS, the water quality parameters were the same for all treatments and corresponded to the technological tolerance of common carp.

The experimental period was from July 10, 2019 – November 20, 2019. Result of growth performance showed that the growth of mixed-sex stock was significantly higher than all-female stocks; (Control=3692.0±590.5g, T2=3438.8±415.4g, T3=3294.1±659.1g). Feed conversation ratio (Control=1.3±0.1 T2=1.5±0.2 T3=1.6±0.5) and SGR% (Control=0.8±0.0 T2=0.7±0.1 T3=0.7±0.1) were similar.

By the results it can be said the all-female common carp technology has neither advantages nor disadvantages compared to the mixed-sex stock. The all-female technology can be beneficial if the consumers need female common carps. It is worth continuing the experiment and examine how the stocks will perform above 3kg body weight.

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Using the principles of precision animal husbandry in fishbreeding
Published November 13, 2012

Aquaculture species such as fish, crayfish, molluscs and plats are a wide range of products, with continuously growing demand worldwide. The reasons for this is that they are cheap and easy-toraise protein sources, thus having significance in food supply especially in developing countries in tropic regions, moreover, the premium category foodst...uffs in developed high income countries are also belonging to this category. World annual total production of 164 million tons (2009) are made up of two sources: 1) marine and inland fisheries landings that are stagnating for several years and 2) aquaculture which is growing dynamically with annual 6% rate between 2000–2009. The latter is accounting for nearly 45% of the total supply due to the depleting marine stocks caused by overfishing. Aquaculture is growing continuously also because the production is safe and can
be planned well. 
Intensive fish production systems are the representatives of precision animal production, several types exist and widespread worldwide. The modern computerized temperate water recirculation plants with several thousand m3 capacity are widespread also in Europe because they make it possible to produce even the most valuable species whole year round. A key issue in the technical/feeding outlay is to meet the demands of the cultured species the best and the operation of the system is to be safe and cost-effective. One condition for this is intensification: enable to produce more product per unit resource input or effort. The facilities need significant amount of energy, thus renewable energy sources are to be favoured for which Hungary has comparative advantages.

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The effect of dissolved oxygen on common carp (Cyprinus carpio) and basil (Ocimum basilicum) in the aquaponics system
Published June 1, 2021

Aquaponics is an integrated system that combines fish farming (aquaculture) and hydroponic plant production. The objective of this study was to examine how the level of dissolved oxygen with or without an air pump affects water quality, fish output and plant growth parameters for common carp (Cyprinus carpio) and basil (Ocimum... basilicum).

Ebb – and flood aquaponics systems (with automatic syphon) was used. Two treatments were set in this experiment, one of which was the aquaponics system without air pump (unit I), where water of the plant bed was pumped two directions, one falling back to the fish tank oxygenating the water the other was pumped to the hydroponics unit. The other system (unit II) was designed with an air pump.

In the course of the study, water quality parameters, such as oxygen saturation, dissolved oxygen (DO), electrical conductivity (EC) and nitrite were significantly different (p<0.05). Total basil biomass was higher in unit II. (5367.41 g). The final biomass of common carp were
2829.45 g ± 79.24 and 2980.6 g ± 64.13 g in unit I and unit II respectively. Weight gain (WG) and specific growth rate (SGR) showed no significant differences (p>0.05) between the treatments. 

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Use of essential trace elements enriched Artemia in the larval rearing of barramundi (Lates calcarifer)
Published July 31, 2012

Artemia is a vital nutriment in the rearing of barramundi (Lates carcarifer), however it’s mineral trace element content does not cover the requirements of the larvae. In our experiment the assumption was wether the cobalt, zinc and manganese concentration of Artemia could be increased during a 24 hours of enrichment period, as well as we wan...ted to investigate the resulted interactions between the elements. For this purpose 50, 100 and 1000 mg l-1 cobalt-chloride treatements (Co50, Co100, Co1000) were applied while in the case of 50 and 100 mg l-1 treatments the enrichment was also complemented with zink-sulphate and manganese-chloride in the same concentrations. According to the results the zooplankton were able to accumulate cobalt in higher amount, and yet zinc and manganese had no significant effect on each other, a strong synergistic effect occurred between cobalt and manganese. After the enrichment period the impact of essential trace element supplemented live feed on the survival and growth of barramundi larvae was also studied. The experiment was carried out by using 15 days-old larvae applying a total of 9 treatments for two weeks (Control, Co50, Co100, Mn50, Mn100, CoZn50, CoZn100, CoMn50, CoMn100), in duplicates. Considering the per cent of survivals, no significant difference was observed between the treatements (P>0.05). In the case of CoMn50 and CoMn100, the loss statistically increased (P<0.05) compared to the Control (80.5±4.95%) group. Our results show, that the Mn100 and CoMn100 treatements resulted in  ignificantly higher (P<0.05 ) in divid ual bod y w eight s, how ever taki ng the survival also into consideration the Mn100 treatements proved to be the most

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Examining the production parameters of European perch (Perca fluviatilis) juveniles under different lighting conditions
Published June 1, 2021

European perch (Perca fluviatilis) is a native predatory fish in Hungary, and a promising new species of fresh water aquaculture nowadays. The European perch can be characterized by a high stress sensitivity during the intensive rearing, thus the optimization of environmental conditions has significant importance in the early life ...stages of fish. The aim of our study was to determine whether the light intensity and darkening of the water by humic acid affect the survival and growth performance of European perch juveniles. The experiment lasted for 28 days. Rectangular aquariums were arranged in 3 lines, the test environment consisted of 24 units. The experiment was set up with 10–10 fish per aquarium, total of 240 individuals. The average wet body weight of the fish at the start of the experiment was 1.69 grams. During the experiment, 6 treatments in 4 replicates were set up. In the first row, we set up 305.6±66.0 LUX (L), in the second row 118.0±24.4 LUX (C), and in the third row (D) 17.0±8.6 LUX illumination was set up. In each row the water of four aquariums were darkened by the addition of humic acid (H) (L, LH, C, CH, D, and DH). At the end of the experiment high survival rate was observed in all treatments. Examining the survival rate, the best results were found in the strongly illuminated treatments (L; LH- SR%=100±0.00). The observed mortality was caused by cannibalism. Regarding the individual body weight, the best results were shown by the treatments where the aquariums were illuminated with lower light intensity (C: 4.66±0.33 grams) and the aquarium water was darkened by humic acid (CH: 4.93±0.15 grams). The results of the C and CH groups were significantly better compared to the other treatments, however, they did not differ statistically from each other. The darkening of the water had a positive effect on the individual body weight of fish reared under full light (L: 3.73±0.28 grams; LH: 4.33±0.28 grams), whereas in the case of fish reared in the lowest illumination, the addition of humic acid did not affect the results (D: 3.78±0.15 grams; DH: 3.80±0.26 grams). In case of SGR (C: 3.64%/day and CH: 3.74%/day) and FCR (C: 0.84 g/g and CH: 0.78g/g) the best results were obtained by the C and CH treatments, also.

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