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Optimizing fish structure in angling ponds focusing on white fish
Published May 23, 2019

According to new amendments of laws, commercial fishing licenses of natural waters shall not be issued from the calendar year 2016 in Hungary. However, the most settlement of white fish to angler ponds originated from natural waters. Currently, there is no sufficient quantity of fish species belonging to this group available to fulfil the settl...ement commitments of fish farmers. The aim of this recent study is to develop a breeding and production technology that is suitable for settlement of large quantities of this fish species of appropriate length of (4–5 cm). The following methods are investigated: aquaculture cage system (pond-in-pond system), monoculture and mixed population with different ratio of white fish in fish structure. Due to the different environmental needs of different fish species, many parameters need to be investigated, for example: stocking density, feeding, oxygen level, monoculture or mixed populations, growth potential and mortality. A preliminary experiment was carried out following the artificial propagation of ide (Leuciscus idus) following a 21-day larval rearing experiment in which the effect of different stoking density was investigated for mortality and growth. On the basis of the expected results, the optimal conditions for the aquaculture cage system will be described, regarding to the white fish stock.

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Preliminary results on Siberian sterlet (Acipenser ruthenus marsiglii) fries rearing under intensive conditions
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;">In our experiments production performances of Siberian sterlet were tested under intensive tank conditions. During the 25 days long experiment effectiveness of weaning to artificial diet of the fish was investigated. Production performances of fish fed on exclusively dry diet from the beginnings were lower than the other two groups. Between the values of sterlets fed on live food also then suddenly vs. continuously were weaned to dry diet there were no significant differences. Based on our results live food feeding could be suggested for the Siberian sterlet larvae for some days but the method of the weaning to dry diet has no significant influence to the production performances.

In 21 days long experiment four different feeding frequencies were tested in Siberian sterlet (~13 g) fingerlings. Dry feed was offered for the fish continuously, 2, 3 and 4 times per day. There were no significant differences between the values of the four treatments. Based on our results there is no high influence of feeding frequency in case of this size group of Siberian sterlet.

During the nursing in two different size groups of Siberian sterlet the optimal daily amounts of feed were aimed to determine. In case of growth values of the group fed at 7% of the total biomass were higher than the other two groups (3 and 5%). Feeding performances of fish fed at 5% were significantly better than fish fed at 7%. Based on our results for ~20 g size of the subspecies at least 5% of total body weight could be suggested.

In case of ~150 g size of the fish the production performances of fish fed at 1% were lower than the other two groups (2 and 3%). Between the values of stocks fed at 2 and 3% there were no significant differences. Based on these results 2% of total body weight of dry feed could be suggested for the Siberian sterlet with ~150 g body weight.

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Effect of fish feed containing two Chinese herbal extracts (Ganodema Iucidum and Lonicera japonica) on the non-specific immune system of Nile tilapia, Oreochromis niloticus (preliminary results)
Published July 16, 2007

The effect of two Chinese herbs (Ganoderma lucidum and Lonicera japonica) on non-specific immune response of tilapia was examined. In addition to the control (no herbs), three diet variations were used. These contained 1.0% of Lonicera, 1.0% of Ganoderma and a mixture of Ganoderma (0.5%) and Lonicera (0.5%). The respiratory burst and phagocytic... activity of blood leukocytes were monitored. Three weeks after feeding, the fish were infected with Aeromonas hydrophila. The results of this study showed that feeding tilapia with Ganoderma and Lonicera alone or in combination enhanced the phagocytosis of blood leukocytes, but not the respiratory burst activity. Both herbs, when used alone or in combination, reduced mortality after challenge with A. hydrophila. The highest mortality was observed in the control fish – 56.66%, and fish fed with Lonicera extract – 43.33% while 30% of fish died in the group fed with Ganoderma and the lowest mortality (20%) was observed when the fish were fed with a combination of the two herbs. It can be concluded that the herb extracts added to this diet act as immuno-stimulants and appear to improve the immune response and disease resistance of tilapia.

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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 effect of different fat content fish feed on the production parameters and meat quality of the hybrid striped bass
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;">The interspecific ’hybrid striped bass’ is the result of cross breeding. Their offspring have got good chances of growth and tolerate extreme water temperatures and the content of dissolute oxygen more than their parents. Furthermore, they are more resistant to diseases. Therefore, the hybrid is perfectly suitable for intensive fishery production.

Our experiment lasted for seven weeks. We analysed the indices of growth and production of the hybrid as the consequence of nurturing them with two feeds of high nutritive value during this period. We examined the content of fat and of fatty acids in the flesh of these fish. There were no considerable differences in terms of weight gain, feed conversion ratio and uneven growth between the two groups, while survival was less likely among the the fish which had consumed more fat. We demonstrated, examining the flesh of the individuals which had consumed feed containing lower fat content, that it was fattier and contained more dry matter than those that had been fed of higher fat content. Besides, the content of omega-3 and omega-6 fatty acids was higher in the fish that had consumed less lipids.

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Study of the Interaction Between Common Carp (Cyprinus carpio) and Silver Crucian Carp (Carassius auratus gibelio Bloch)
Published December 6, 2005

Some of the main questions in the fish farming are the good manuring and the success of the feeding. For the best result is very important that only those fishes take place in the fishponds what we want. It seems to be easy but difficult to do. One of the main challenges of the successful fish production in fishponds, is to rid ponds of the sil...ver crucian carp. In the course of the experiment, carp fry were stocked in 5 nursing ponds at the same stocking rate, with different (0-, 50-, 100-, 150-, 200%) stocking rates of silver crucian carp fry, respectively. During the rearing season, weekly test fishings were made to control the growth of the fishes. At the end of the experiment, the yield/hectar and the growth rates were calculated. The experiment proved that the presence of the silver crucian carp in the fishponds causes lower growth rates and productivity in common carp. In the control pond (without silver crucian carp), the average weight of the common carp was 25 g and the yield/hectar was over 900 kg, while in the pond with the most silver crucian carp, the average weight of the common carp was 9 g and the yield/hectar was only 158 kg.

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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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Coherence and connection between the good pond culture practice and the environment conscious management
Published April 11, 2007

According to the data indicating the decline and restructuring during the past decade, as well as the trend in the European Union member states, it can be expected that the role of traditional agriculture and fish production in direct rural employment decrease further. This also values those strategic directions for restructuring that will lead... fishculture from quantity driven to quality production along with sustainable development (i.e. environmental conscious production) and multifunctional farming. This way the economic and social tensions caused by the concentration of the production and labour output can be mitigated.
It is laid in the 1257/1999 Act on rural Development that farmers that enrol the agri-environmental scheme should follow the “Good Agricultural Practice” on the whole managed area. In case of agri-environmental schemes this is a precondition for which no grants are given.
The adaptation of “Good Agricultural Practice” in fishproduction,where it is called: “Good Pond Culture Practice” is considered important on the basis of the above mentioned. This programme is undertaken in co-operation with the Research Institute for Aquaculture, Fisheries and Irrigation, University of Debrecen, Faculty of Agricultural Economics and Rural Development and the Association of Hungarian Fish Farmers and Product Council.
The European Commission proposed the formulation of the European Fisheries and Aquaculture Fund (EFAF) for the period 2007-20013, which will replace the Financial Instruments for Fisheries Guidance (FIFG), but it also consists of several new elements and will be working differently, too. According to the proposal the budget for the Fund will be nearly 5 billion EUR (4963 million EUR). The development level of aquaculture and fisheries and the social and economic significance in the given member state will be considered when distributing the Fund between the Member States.
According to the plan the Fund is organised along five priority axes, of which the most important for the Hungarian fisheries sector is No. II: Aquaculture and the processing and marketing of aquaculture and fisheries products. The main measure areas are the followings:
1. investment support for aquaculture;
2. support for aquatic-environmental schemes;
3. environmental- and animal health issues;
4. investments in processing and marketing
In case of accessing support under measure area No. 2 farms are obliged to meet the requirements of the scheme beyond the “good management practice” for 5 years, which is to be supervised by the approved body of the Member State. For this reason our work is considered to be substantial.
Approval of the application of “Good Pond Culture Practice” is based on two elements: first the prevailing environmental and nature conservation regulations, as well as the list of controllable conditions in the new agri-environmental agreements are to be met. “Good Pond Culture Practice” are to be conducted on the whole farm area. Its main elements are:
- nutrition management,
- feeding,
- pond maintenance,
- stocking,
- harvesting,
- animal welfare (storage and over-wintering).

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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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