The marketing fish research in the Czech Republic is directed to the sale of the fresh water fish, which are typical for our country. The consummation of fresh water fish has a long tradition in the Czech Republic, by contrast the marine fish are of the business in the modern life, which made possible to import this raw from the seaside country. In spite of the long term of the being fish in our market its consummation has got a low level. I directed above all to the young people and their board custums considering to the fish consummation in my dissertation. More than two third of inhabitants consumms fish, that means that it is a big chance for the motivation directed to the higher consummation of the fresh water fish. The Czech people eat much more salt water fish than fresh one. The reason is the wider choise of the salt water fish in the market , its better preparation for cooking purposes and lower prices than by the fresh water fish products. There is a low or almost no choice of the fresh water fish meals in the restaurants. With the boarder fish advertisiment by chefs and education it is possible to reach the more frequent using of fresh water fish in the reastaurant´s menus, which the young generation likes.

The successful production of quality early fish stages is crucial for artificial rearing fish species. Nevertheless, it is quite a problematic process, because fish as poikilothermic organisms are highly sensitive to various environmental conditions. Moreover, both fish embryos and larvae are more affected by biotic and abiotic factors (such as predation, stocking density, temperature, light, pH, salinity, oxygen saturation, feeding availability, or their interactions) than older juveniles or adults. Most fish processes such as reproduction, metabolism, survival, development and growth can be considerably (positively, negatively or not) influenced by these conditions. Therefore, it is important to understand their impacts on fish stages during embryonic, larval, juvenile, adult, and eventually the senescent period. Then, following the application of new knowledge to the practise, especially species- and age-specific optimal conditions, should result in higher survival, better growth rate, well developed fish without deformities and lower cannibalism. The objectives of the present thesis were to assess the effect of water temperature and light intensity on the early development (embryonic and larval period) of African sharptooth catfish as a perspective fish species for freshwater intensive aquaculture. Due to its great characteristics (for instance fast growth, ability to breathe atmospheric air, rearing at high stocking density) this species can meaningfully contribute to the global aquaculture production which is expected to rise in the coming years. However, there are still some difficulties in the early rearing African sharptooth catfish regarding the cannibalism, feeding, survival and necessity of detailed information about the effects of some abiotic factors and their interactions.

This thesis consists of seven published papers on free-living amoebae (FLA), members of Amoebozoa, Excavata: Heterolobosea, and Cercozoa, and covers three main topics: (i) FLA as potential fish pathogens, (ii) diversity and phylogeography of FLA, and (iii) FLA as hosts of prokaryotic organisms. Diverse methodological approaches were used including culture-dependent techniques for isolation and identification of free-living amoebae, molecular phylogenetics, fluorescent in situ hybridization, and transmission electron microscopy.

Předkládaná práce by měla čtenáře blíže seznámit s chováním ryb, které tito živočichové vykazují vůči vlečným sítím během vzorkování pelagiálu vodních těles. Zaměřuje se na oblast v ústí tralu, kde je spektrum reakcí nejširší. Některé specifické rysy chování jsou uvedeny na příkladech z mezinárodních výzkumů v teoretické části. Jsou zde rovněž přiblíženy základní techniky, používané při studiu chování ryb ve vztahu k vlečným sítím. Praktickou částí je dvouletý výzkum (2009 a 2011) chování ryb na českých údolních nádržích Želivka a Římov ve vztahu k tralovým sítím. Chování ryb v ústí pelagického tralu bylo monitorováno prostřednictvím vertikálního sonaru SIMRAD EK 60 o frekvenci 38 kHz. Předmětem výzkumu bylo studium reakcí jednotlivých ryb se zaměřením na vertikální složku jejich pohybu. Zjišťovali jsme rozdíly mezi denní a noční aktivitou ryb, rychlost a sklon ve vodním sloupci, přímočarost trajektorie pohybu, souvislost mezi velikostí ryb a jejich rychlostí, a v neposlední řadě také vliv abiotických faktorů, které únikové chování podstatně ovlivňují. Znalost tohoto typu chování pomůže vypovědět o selektivitě zařízení, kterou je vhodné znát pro efektivní průzkum zdejších nádrží. Stejně tak užitečné jsou nové informace o vlastním chování ryb, které jsou přínosem nejen pro ekologii.

Aim of this work were to assessed the impact of feeding, temperature, stocking density, fish size and water temperature on ammonia excretion and oxygen consumption of Nile tilapia (Oreochromis niloticus) in recirculating system. Concentration (saturation) of oxygen, water temperature and pH were measured using multimeter and concentration of ammonia was assessed by direct Nessler method. For assessing of effect of fish size, three groups of tilapias weighed 25, 65 and 140 g were established, each group in four replicates. For assessing of effect of feeding was tilapias (body weight 65g) divided into groups fed continuously, two meals per day and four meals per day, each group in four replicates. For assessing of effect of stocking density was tilapias (body weight 65g) divided into groups of 20, 50 and 80 kg.m-3, each group in four replicates. All experiments were performed for water temperature of 23, 27 and 31 °C and for fed and starved fish. Mean daily oxygen consumption was higher for smaller fish categories than for bigger ones and grow rapidly after feeding. The kind of feeding had impact on diurnal fluctuation of oxygen consumption. It was also confirmed that tilapia can survive low level of oxygen concentration for a quite long period.

This diploma thesis is focused on culture of pikeperch under controlled conditions and tested the optimal environmental conditions for their good growth and survival. The aim of this work was to test the effect of different oxygen saturation on survival, growth, feed intake, feed conversion rate and condition of pikeperch Pikeperch (mean body weight 10.3 g; n=810) habituated to artificial feed were placed in culture tank of the same volume of water and environmental conditions. Fish were fed ad-libitum. Three different oxygen saturations were tested in triplicate: normoxia with saturation of 85-95% O2, hypoxia with saturation of 55-65% O2 and hyperoxia with saturation of 145-155% O2. The experiment lasted 82 days and was divided into five periods. Biometric measurements of fish were performed at the end of each period. Cumulative survival, fish growth, amount of received feed, specific growth rate and condition factor were used for evaluation of our results. The results showed the positive effect of hyperoxia on feed intake and growth of fish. Slower growth was observed in hypoxia. The mean weight gain for the whole experiment was followed: normoxia 28.2 g, hyperoxia 37.7 g and hypoxia 22.9 g.

Pond harvesting is an integral part of fish farming procedures in pond culture and overall fish production. This study was aimed at the evaluation of environmental conditions during pond harvesting, based on the comparison of values monitored in the trawl-net with fish located in a harvesting pit and outside it. The monitored parametres comprised the oxygen content and saturation, temperature, pH, conductivity and turbidity. The monitoring was performed on three autumn harvests (Potěšil, Rod, Jaroslavický dolní) and two spring harvests (Vrbenský přední and Vrbenský nový), always during the fish removal from the net (seine). The monitored determinants were recorded in 30-min intervals inside the net with fish and outside it in 15m distance. During the statistical comparision of the oxygen content and saturation in the net and outside it with the count on fish biomass was statistically signifiant differences in the four of twelve raids evaluated, which means keeping fishes in the net during the yielding was adequately treated by installation of fresh water jet.When the fresh water jet had been stopped worsen of the conditions in the fish net and even in the harvesting pit appeared.

The aim of the present study was to assess an influence of two different therapeutical concentrations of peracetic acid on selected haematological and biochemical parameters in grass carp (Ctenopharyngodon idella). Fish were radomly distributed to aquaria and exposed to concentrations of 0 mg.l-1 PAA (control group), 1.0 mg.l-1 PAA (P1 group), 3.0 mg.l-1 PAA (P2 group). Almost total mortality of fish was observed in the concentration 3.0 mg.l-1 PAA during the treatment comparing with the P1 group and untreated control where no mortality was observed. After the end of the experimental exposure of fish to peracetic acid, the sampling of blood has been realised. The samples of the blood were examined in order to determine haematological and biochemical parameters. Consequently, there were no significant differences (p<0.05) in a haematological profile of fish exposed to concentration of 1.0 mg.l-1 PAA. Goblet cells count and size have risen, that caused exposure of fish to peracetic acid. In the biochemical profile of fish, significant changes (p<0.01) in three parameters were found after exposure of fish to peracetic acid in concentration 1.0 mg.l-1. Changed parameters were: aspartate aminotransferase, creatine kinase and lactate dehydrogenase. The changes were moderate and it can be supposed that these changes are reversible. No significant change (p<0.05) in haematological parameters points out to the minimum negative influence of recommended therapeutical concntration (1.0 mg.l-1 PAA) to the health of C. idella.

The Chabarovice coal mining pit arose by flooding the former strip mine area for brown coal. After filling, the pit area should reach about 225 hectare, total volume of water 34.4 mil. m3, average depth 15,6 meters with maximum of 23,3meters. It is assumed that the pond and adjacent areas will be used for recreation usage after completion of recultivation and ground shaping. I have performed the investigations in June and in August 2004 - 2005, using basic ichthyological methods. The data about recruitment were collected by the littoral seine net and adult fish (older than one year) were investigated by gillnets nets. Fish was determinated to genus, individually measured by slide caliper (fry) and by measuring plate (adult fish). The lenght of fish body (SL-standart lenght) was measured in millimeters and fish were weighted separately (W v g). In the year 2005, also scales were taken from individual fish for the age assesment. Obtained data were processed with regard to performed biomanipulation measures in individual sectores. Nine fish species and one hybrid were recorded by the monitoring with gillnets nets. The most numerous fish were juveniles and adults of rudd with SL 74 {--} 300 mm and the weight up to 618 g. The fish species with the strongest impact upon the pit ecosystem function is conitnuously the perch with the dominance of individuals with SL 46 to 337 mm and weight zup to 850 g.

This diploma thesis deals with the risk associated with fish production. Selected risks are further taken into account. The risks are further described and addressed using the FMEA matrix. The thesis contains a mathematical model that solves the optimal population of the pond in order to maximize profits. The model includes fixed input parameters, which includes the price of hatchery material and the market price of fish. Furthermore, the model contains random input parameters that are limited by the intervals and includes the growth coefficient and the size of the population in the pond. The optimization model is based on simulated data, which are based on real data and statistically determined estimates. The used data are processed into tables in MS Excel for better visualization. GAMS software is used for software implementation of the model.