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Selected aspects of intensively cultured European whitefish (Coregonus maraena, Bloch) and peled (Coregonus peled, Gmelin)
ŠEBESTA, Roman
Maraena whitefish and peled are considered to be economically important fish species. This Ph.D. thesis deals with testing of selected aspects which show potential for improvement of quality and effectivity of larvae and juveniles of both fish species in recirculating aquaculture systems. The whole Ph.D. thesis includes 9 chapters described in 125 pages. In chapters 2-8, there are described the individual factors which can influence quality of intensive rearing of mentioned fish species. The effect of light intensity and tank wall colour on growth and survival of peled larvae is tested in chapter 2. The effect of different temperature on growth and survival of maraena whitefish larvae is presented in chapter 3. The effect of various stocking density on growth and survival of maraena whitefish larvae is given in chapter 4. The influence of different feeding strategy on survival, growth, and intestine and liver development of maraena whitefish larvae is being shown in chapter 5. The effect of various weaning time and co-feeding duration on growth and survival of peled larvae is described in chapter 6. The effect of variable water oxygen saturation on growth and haematological profile of peled juveniles is shown in chapter 7. The prevalence of deformities in intensively reared peled and comparative morphometry in intensively reared fish compared to pond-reared fish is described in chapter 8. Ph.D. thesis contains important advices which can be used in fishery practise and at the same time they can prevent from elevated fish mortality.
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Impact of teperature, fish size and feeding on oxygen consumption and ammonia excretion in the african catfish (Clarias gariepinus)
KOMENDOVÁ, Jana
Aims of this thesis were to assesed the impact of feeding, temperature of water and fish size on ammonia excretion and oxygen consumption in Clarias gariepinus in recirculating system. Fish were divided in 8 weight categories from 21 to 2495 g. Experiments were performed under four temperatures: 22°C, 25°C, 28°C and 30°C. Fish were acclimatized, light conditions were: 14 hours of light period and 10 hours of dark period. Feeding was provided fed four times a day. Starved fish were measured. Measurements were held every two hours. Oxygen consumption was measured by multimeter and ammonia excretion using Nessler?s method. Average daily oxygen consumption in fed fish was dependent on temperature and average individual weight of fish, varied from 10.5 to 96.6 mg O2/kg/h and in hungry fish from 4.3 to 61.8 mg O2/kg/h. TAN excretion varied from 0 to 59.9 mg TAN/kg/h in fed fish and from 0 to 60.8 mg TAN/kg/h in hungry fish. Oxygen consumption increased with increasing temperature. Ammonia excretion was very unstable at all temperatures in all weight categories. Fish had higher ammonia excretion in light period of experiment.
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Practical use of Persteril for the prevention of fungal infections of fish roe and its effectiveness in antiparasitic baths cyprinids compared with used liquids
FOŘT, Ondřej
Persteril (Acidum peraceticum) is a trademark used for a disinfectant with peracetic acid as an active ingredient. It is highly effective biocide and has extensive application possibilities with regard to environmental friendliness, it also has the widest range of disinfection efficacy. The practical part took place in the Genetic centre hatchery at the FROV JU in Vodnany. Persteril? was used for Short-time bath followed by rearing roe in the recirculating system and for short-time bath followed by rearing roe in the flow system. Both versions are breeding quite well; Persteril? detects fungal infection of fish roe in comparison with other liquids, as well as it leaves smaller or no residue in the water or out of the water until the evaporation (according to the concentration).
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Possibilities of use technical disinfection of water in fish farming
BROŽ, Pavel
Disinfection of water in fish farming is becoming increasingly important. For these measures, there are different ways of water treatment. The aim was to evaluate selected water treatment facilities in terms of economic performance. This work compares UV sterilizers and ozonizers on the basis of their technical parameters and market prices.
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