The aim of the study was to determine the impact of diet (natural and formulated feed) on the chemical composition and fatty acids profile of the harvested fish. The content of dry matter in fish flesh resulting from the formulated diet was higher vs. the natural diet (23.94?1.24 % vs. 19.66?0.82 %) with nitrogenous compounds (60.24?2.82 % vs. 72.12?1.75 %), total fat content (24.81?4.51 % vs. 6.14?2.85 %) and ash (7.55?1.28 % vs. 10.54?1.53 %) respectively. The spectrum of fatty acids was determined by gas chromatography using Varian 3800 equipment. Tench fed on a formulated diet in the recirculating system had a significantly higher content (P< 0.05) of monounsaturated fatty acid (MUFA = 43.04?1.68 %) and n-6 polyunsaturated fatty acids (PUFA = 15.47?1.07 %) in their flesh compared to the flesh of fish reared in earth ponds on a natural diet - MUFA (32?5.29 %) and n-6 PUFA (13.6?1.66 %). Tench fed on a natural diet in earth ponds proved to have a significantly higher content (P< 0.05) of n-3 PUFA (16.8?4.38 %) and ? PUFA (30.3 ? 5.3 %) than tench reared in the recirculating system - PUFA n-3 (10.05?0.85 %) and ? PUFA (25.52?1.07%). The ratio n-3/n-6 for fish from earth ponds was 1.2; for fish from the recirculating system the ratio was 0.65. The results show a significantly higher composition of n-3 PUFA in flesh of tench from earth pond with natural food compared to fish on an intensive feeding diet in the recirculating system which showed a higher content of n-6 PUFA.

In this project, the eggs of tench (Tinca tinca) were used for the evaluation of changes in fatty acid (FA) composition and lipid classes during in vitro ova ageing until the occurrence of over-ripening. Stripped ova of 6 females were collected separately and stored in sterile cell culture plates in an incubator at 20 °C for up to 24 hours post stripping (HPS). Stored ova were fertilized at 0, 2, 4, 6, 8, 10 and 24 HPS. Egg eyeing and hatching rates were assessed as indices of egg quality. Upon fertilization at each HPS, samples were taken separately frozen in liquid nitrogen and stored at -80°C till further analyses. Differences in the FA and lipid composition and embryo survival rates at the different fertilization times post-stripping were evaluated. The lipid fraction was extracted from the oocytes according to Hara and Radin (1978). The lipid content of the samples was determined gravimetrically from total extracted lipid. The FA were then analysed with a gas chromatograph equipped with a flame ionisation detector and PVT injector. The peaks were identified by comparing their retention times with those of authentic standards. Major lipid classes and the phospholipid classes were separated according to (Olsen and Henderson, 1989). Quantitative analysis of the separated lipid- and phospholipid classes was done by scanning the plates after derivatisation with a CAMAG TLC Scanner 3 (Camag, Switzerland). Identification of the lipid classes was performed by comparison with authentic standards applied on the same plate. In present study no significant changes were observed in lipid content and composition during storage of eggs until over-ripening. As well FA composition did not change over time indicating another reason of deterioration of oocyte quality than the proposed lipid oxidation. However individual fishes in this study showed much different fertilization rates that corresponded with their levels of cholesterol and triacylglycerols in minor degree.

This theses deals with the storage length of artificially spawn of hard roes of Tench (Tinca tinca) during different temperatures at the time before the semen discharging and activation to fertilization, hatching and consequent survival of fish hatchery throughout changeover from the embryonic to larval life period (beginning of active food intake). Homogeneous assortment of hard roes obtained from hormonally induced artificial hatching of 6 spawners has been used for this experiment. Samples of hard roes were put into plastic bowls and covered, immediately after artificial hatching. Subsequently, they were placed into tempered, thermo-isolating containers with temperatures of 5, 10, 15, 20, 25 and 30 °C. In time intervals of 0.5; 1; 1,5; 2; 3; 4; 6; 8 and 10 hours, a small amount of hard roes were taken away from each temperature (estimated 50 -100 pieces) and put into dry, glass beakers (in 3 repetitions in each temperature combination and length of storage). Subsequently, the semen discharging from 6 milters was carried out and activation by water was performed. Incubation took place in non-sticking environment. During the incubation, or more precisely during the consequent storage of embryos through temperatures between 19-20.5 °C, water was changed daily. Fertilization was evaluated 48 hours after fertilizing. Hatchery was determined 48 hours after beginning of hatching of first specimen. After changeover from embryonic to larval period of ontogenetic development, living food was offered to hatching fish (artemia sp.). Thereafter, the amount of hatched fish with filled intestines was counted. Ascertained values were depicted as a percentage from the total number of seeded hard roes as well as fertilized hard roes with the use of statistic methods (two factors Anovy with the repetition). The highest level (in statistic evaluation on the importance level alfa = 0.05) of hard roe hatchery was accomplished throughout the length of possession and temperature 1 hour/ 25 °C (68.0 +- 3.1 %). The high level of hatchery was maintained by hard roes stored for 2 hours, afterwards a gradual value decrease was registered. Similarly, that was achieved with hatching parameter, where the high level of hatching was achieved with hard roes possessed for the period of 3 hours (except temperature of 30 °C), afterwards the hatchery was decreased. Pursued survival and food intake parameters of hatched fish (from the practical point of view) confirmed above stated dispositions. The high hatchery from placed hard roes was maintained for 1.5 - 3 hours (except 30 °C), thereafter there was its gradual decrease. In the time of 8 hours (temperatures 5 - 20 °C), the survival of 1.2 +- 1.8 %, was found out, with the rest, the survival was nearly zero.

Different cryoprotectant media for cryopreservation of embryos has been tested on model species, i.e. common carp (Cyprinus carpio) and common tench (Tinca tinca). The aim of the study was to obtain such cryoprotectants, which will be acceptable for freezing embryos up to the temperature {--}196 oC. Cryoprotectants of 10 % and 20 % methanol or 10 % and 20 % glycerin have been tested on the tench for 21 minutes of incubation on embryos of four stages, meaning at 11, 17, 23 and 29-hrs after activation of gametes. The results showed that the tench embryos were most resistant either to low temperature and or to the application of cryoprotectants in the stage of 29-hrs post gametes activation. On the other hand lower resistances were obtained in the stage of 11-hrs post gamete activation. Embryos of carp 2, 6, 22, 24 and 42-hrs after gametes activation at temperature 18 and 22 oC have been used for testing of concentration series of cryoprotectant methanol and two solutions marked VS1 and VS2 after previous disruption of egg envelope in enzyme alcalaze solution. Results showed linear decreasing resistance of embryos depending on increasing concentration of cryoprotectant methanol. Hatching success even at highest concentration of solution VS1 and VS2 has not declined below 70 %. Achieved results with solution VS2 have been subsequently used for freezing of carp embryos by special methods in cryobiology {--} vitrification. First results showed up to 4 % success of survival after freezing of embryos at {$-$}196 oC.

This thesis aims to assess the possibility of the usage of various biological fixatives for fish cell and tissues samples in order to extend its storage for later flow cytometric measurement of DNA content. The model species chosen were sterlet and tench, from which three types of samples were obtained: blood and fin tissue of subadult / adult individuals and tail tissue of hatched larvae. Altogether 13 fixation methods were tested for each type of sample of both model species. Methods were chosen based upon their easy feasibility and low time-consumption. The samples were measured on flow cytometer in native state immediately after sampling and placing in physiological saline and after 1, 5 and 10 days of fixation during which they were stored in a fridge or in a freezer at -80 ?C. Their analysis was carried out simultaneously with standards native cells from tench fin tissue when investigating sterlet samples, and commercially available fixed trout erythrocytes for tench samples. A fluorochrome used was 4',6-diamidine-2'-phenylindole dihydrochloride (DAPI; with excitation/emission maxima 358 / 461 nm). Based on the evaluation of coefficients of variation (CV) of fixed samples and the changes in their fluorescence levels in comparison with native state, optimal procedures for extended storage of all types of samples from both model species are suggested.

La presente Tesis Doctoral tiene como objetivo profundizar en los conocimientos sobre ritmos biológicos y comportamiento alimentario de tres especies de peces teleósteos de interés en acuicultura: tenca (Tinca tinca), trucha alpina (Salvelinus alpinus) y lubina (Dicentrarchus labrax).Con este fin se ha investigado la influencia de factores bióticos y abióticos en la sincronización de los ritmos de actividad locomotora y alimentaria, así como el carácter endógeno y/o exógeno de estos ritmos. A su vez, se ha profundizado en el comportamiento individual de truchas alpinas mantenidas en grupo, mediante una nueva metodología que permite estudiar los ritmos de demanda voluntaria de alimento y la autoselección dietaria de los individuos. Asimismo, se ha analizado la influencia de los niveles endógenos de melatonina, modificados mediante la administración de melatonina exógena y de su aminoácido precursor (triptófano) en la dieta, sobre la concentración de cortisol y el ritmo de actividad locomotora en lubina. / This Doctoral Thesis deeps into the knowledge about biological rhythms and feeding behaviour in three teleostean fish species of interest in aquaculture: tench (Tinca tinca), Arctic charr (Salvelinus alpinus) and European sea bass (Dicentrarchus labrax). With this aim, the influence of biotic and abiotic factors has been researched in the field of synchronization of locomotor and feeding rhythms, as far as the endogenous or exogenous character of these rhythms. Moreover, individual feeding behaviour of Arctic charr kept in groups has been studied trying a new methodology which allows the monitoring of feeding demands and dietary self-selection of individuals. Furthermore, influence of endogenous melatonin modified through exogenous melatonin and its precursor amino acid (tryptophan) administration in the diet, in the cortisol levels and locomotor activity rhythms in sea bass were analysed.