Thesis (M. Sc. (Ichthyology & Fisheries Science))--Rhodes University, 2004.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 153-173). Also available via the Internet.

Goldfish ova begin rapid maturation in November. Maturation is completed in June and July. Seasonal cycles in mature and resorbing follicles were correlated with changes in basophil counts of the pituitary gland. Cytological evidence confirms the expected pituitary control of cyclic ovarian activity. Resorbing follicles are found all year but are more abundant during sexual maturity, and are particularly numerous in fish which failed to spawn. Goldfish injected with extracts of salmon pituitary for twelve days showed no cytological changes in the ovary. It is concluded that the granulosa is responsible for removal of resorbing ova and that these resorbing ova are the means of removing surplus eggs. / Science, Faculty of / Zoology, Department of / Graduate

Goldfish (Carassius auratus) of identical thermal and dietary history were subjected to long-day (16 hours) and short-day (8 hours) light periods. Variation in the ability of these groups to withstand temperature extremes were compared during the fall and winter of 1955 and during the spring and summer of 1956. In the fall and winter group fish exposed to 8 hour daily illumination were consistently more resistant to cold and less resistant to heat while the reverse was true of the 16 hour group. In the spring and summer fish the differences were not as marked and were generally in the opposite direction. In general, the data showed that size as well as sex of the goldfish tested modified the observed resistance. At both seasons, fish exposed to shorter daily illumination had higher tissue phospholipid and cholesterol than those exposed to longer illumination. Phospholipid and cholesterol were also compared in the different sexes. / Science, Faculty of / Zoology, Department of / Graduate

Ten different fats (three in duplicate) including natural and hydrogenated fats were arranged in four series of diets to allow a range in degree of saturation of diet in each series. These were fed to 1300 goldfish (100 fish per fat diet). The degree of unsaturation of fish lipid altered in accordance with the degree of unsaturation of the diet and the tolerance of the fish to high and low temperatures was modified. In none of the four series was there a precise correlation between melting point of total lipids and degree of tolerance to high and low temperatures. Since total lipid is not necessarily protoplasmic lipid it is possible that the degree of unsaturation of protoplasmic lipids (phosphatides) and temperature tolerance of the fish would show a more precise correlation. Changes occuring in water content, lipid content, and lipid constituents of fish tissues and iodine values of total lipid were studied in goldfish acclimatized to 5°, 15°,20°, and 35° C. Water content increased while lipid content decreased with a rise in the temperature of acclimatization of fish. The cholesterol : phospholipid ratio varied inversely and the cholesterol : fatty acid ratio varied directly as both the water content and temperature of acclimatization. Iodine values of the total fish lipid increased with a decrease in temperature of acclimatization. It is concluded that in the process of acclimatization to different temperatures, changes in the degree of unsaturation of total lipid as well as possible changes in permeability to water occur and that both factors may be of importance in resistance of the fish to further thermal changes. / Science, Faculty of / Zoology, Department of / Graduate

The effects of dietary phospholipid and cholesterol upon the body lipids and cold resistance of the goldfish (Carassius auratus) were studied. Two series of diets were used to compare the effects of these supplements in the presence and absence of a large oil supplement. It was found that dietary phospholipid and cholesterol both tend to increase cold-resistance of the goldfish, the relative effectiveness of these treatments varying with season and with duration of dietary treatment prior to chilling. The increased cold resistance afforded by dietary cholesterol or phospholipids was closely correlated with the increased cholesterol content of the tissues, but only weakly correlated with the less modified phospholipid content of the tissues. Although feeding these diets also resulted in definite changes in moisture content, total lipid content, unsaturation of total lipids and cholesterol/ phospholipid ratio, no obvious correlation between these factors and cold resistance of the goldfish was noted. In addition to diet, it was found that cold narcosis, season, and size, as well as sex of the goldfish tested, modified the observed cold resistance. / Science, Faculty of / Zoology, Department of / Graduate

Thesis (doctoral)--Université Louis Pasteur de Strasbourg, 1972.

Thesis (doctoral)--Université Louis Pasteur de Strasbourg, 1972.

The purpose of this study was to investigate the mechanism(s) of the preference of sexually mature male goldfish for sexually mature female goldfish. First, the effect of reproductive condition on the sexual behaviour of male goldfish was examined to determine the mechanism(s) of the behavioural preference of mature males for mature females. Second, the effect of reproductive condition of the male on the response of the olfactory bulb electroencephalogram (EEG) to biological olfactory stimuli was examined for the electrophysiological correlates of the behavioural mechanism(s). The sexual behaviour of male goldfish is affected by reproductive condition. Regressed male goldfish do not demonstrate sexual behaviour. The sexual behaviour of mature male goldfish appears to be regulated by two mechanisms. A general tendency of the mature male to chase female goldfish seems to be regulated by an all-or-none mechanism which is activated when spermiation (release of sperm into the sperm duct) occurs in the male. A second mechanism appears to regulate the preference of mature male goldfish for sexually mature female goldfish. The preference for mature females is not directly dependent on spermiation since mature (spermiated) males with gonadosomatic indices (GSI) below 3.5 do not chase mature females preferentially. Mature males with a GSI above 3.5 chase mature females significantly more than regressed females, and a marked peak in the preference for mature females is observed for males with GSIs of 3.5-4.0. An earlier behavioural study suggested that the preference of mature males is a response to a pheromone from the mature females. Therefore, it might be expected that the neural activity of the olfactory system of mature male goldfish would respond differentially to an olfactory stimulus derived from mature female goldfish. The electrophysiological studies of this thesis indicate that a selective response to the stimulus derived from mature females is not evident in the olfactory bulb EEG of mature males. However, the amplitudes of the spontaneous EEG and the responses of the EEG to olfactory stimuli are significantly greater in the olfactory bulb of mature male goldfish than in that of regressed male goldfish. The EEG amplitude is correlated with the maturation of the testes, and gonadal hormones and/or other hormones may affect the EEG. The significance of the increase in EEG amplitude with reproductive condition is discussed in relation to the mechanisms of sexual behaviour. / Science, Faculty of / Zoology, Department of / Graduate

published_or_final_version / Zoology / Master / Master of Philosophy