Orientador: Silmara Marques Allegretti / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-15T15:01:23Z (GMT). No. of bitstreams: 1 Barreto_Ermelindo_M.pdf: 2333180 bytes, checksum: 51b623e799efcc142a93cd0b22a890d3 (MD5) Previous issue date: 2009 / Resumo: O Brasil possui diversas espécies nativas de peixes com grande potencial para exploração na aquicultura. Entretanto, a maioria delas carece de estudos científicos e tecnológicos que permitem a máxima viabilidade zootécnica e econômica. Dentre as espécies de peixes nativas da América do Sul, o pacu, Piaractus mesopotamicus (Holmberg, 1887) é uma das mais cultivadas em pisciculturas de todo o Brasil. O pacu é uma espécie onívora, nativa da Bacia do Rio da Prata, ocorrendo principalmente nos rios Paraná e Paraguai e seus afluentes, adapta-se a diversos sistemas de criação, tem excelente crescimento e conversão alimentar. Sua alta capacidade reprodutiva, crescimento rápido e fácil aceitação comercial, fazem desta espécie uma das preferências no cultivo de peixes no território brasileiro. No período de julho de 2008 a setembro de 2009 foram examinados 142 pacus de tamanhos variados, coletados nos tanques do Centro de Pesquisa e Conservação de Peixes Continentais - Instituto Chico Mendes de Conservação da Biodiversidade - CEPTA/ICMBio, Pirassununga, SP. Os peixes foram medidos, pesados e determinados o sexo e maturidade sexual. Foram encontrados Rondonia rondoni (prevalência de 63,38%, intensidade média de 2589,59 vermes/peixe e abundância média de 1641,29) e Goezia sp. (prevalência de 51,41%, intensidade média de 2,52 vermes/peixe e abundância média de 1,29). Os conteúdos gastrointestinais foram divididos em 3 grupos alimentares: G1 (essencialmente matéria vegetal), G2 (mistura de vegetais com ração) e G3 (essencialmente ração). As análises estatísticas demonstraram haver relação entre o número de R. rondoni presentes no peixe e o grupo alimentar (P<0,0001), sendo o grupo G1 com a menor média no número de vermes (207 vermes/peixe), o G2 com a maior média (4198,42 vermes/peixe) e o G3 com 403,54 vermes/peixe. Outro resultado significativo mostrou que o tanque também influenciou na característica da infecção por ambos os nematódeos: no tanque com grande quantidade de vegetação as prevalências eram baixas e as intensidades altas e tanques sem vegetação houve uma elevação na prevalência e diminuição na intensidade de infecção. / Abstract: Brazil has several native fish species with great potential for exploitation in aquaculture. However, most of them lack scientific and technological advances that allow for maximum performance and economic feasibility. Among the fish species native from South America, the pacu, Piaractus mesopotamicus (Holmberg, 1887) is one of the most cultivated in farms throughout Brazil. Pacu is an omnivorous species, native to the basin of the River Plate, occurring mainly in the Paraná and Paraguay rivers and their affluents. It is a species adapted to different farming systems, it has an excellent growth and feed conversion. Their high reproductive capacity, rapid growth and easy commercial acceptance, make this species very attractive for fish cultivation in the Brazilian territory. A total of 142 specimens of Pacu of different sizes were collected in tanks of the Center for Research and Conservation of Fish Continental - Chico Mendes Institute for Biodiversity Conservation - CEPTA / ICMBio, Pirassununga, SP and examined from July 2008 to September 2009. The fishes were weighed, measured and classified according to sex and sexual maturity. The gastrointestinal helminths found were: Rondonia rondoni (prevalence of 63.38%, mean intensity of infection of 2589.59 worms/fish and mean abundance of 1641.29) and Goezia sp. (prevalence of 51.41%, mean intensity of infection of 2.52 worms/fish and mean abundance of 1.29). The gastrointestinal contents were divided into three food groups: G1 (mainly vegetable matter), G2 (mixed vegetables with fish food) and G3 (fish food). Statistical analysis showed relationship between the number of R. rondoni and food group (p <0.0001). G1 with the lowest average in the number of worms (207 worms/fish), G2 with the highest average (4198.42 worms/fish) and G3 with 403.54 worms/fish. Another significant result showed that the maintenance tank also influence the characteristic of infection by both nematodes. In tank without vegetation there was an increase in the prevalence and decrease in the intensity of infection. / Mestrado / Mestre em Parasitologia

Orientador: Felix Guillermo Reyes Reyes / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-21T10:37:11Z (GMT). No. of bitstreams: 1 Rezende_RenataAntunesEstaianode_M.pdf: 1522270 bytes, checksum: a0ea23b47147c504a5e5f70c7a0d1fbd (MD5) Previous issue date: 2012 / Resumo: A piscicultura no Brasil tem crescido de maneira significativa ao longo dos últimos 20 anos, refletido pelo aumento da produção com elevadas densidades de estocagem. Com a intensificação da atividade aquícola, o surgimento de surtos causados por vários agentes etiológicos tornam-se cada vez mais freqüentes, dentre eles as bacterioses. Para combater o agente responsável por essas enfermidades, muitos antibióticos são utilizados de maneira ilícita, podendo, além de não apresentar efetividade durante o tratamento, causar letalidade aos animais e danos ambientais. Atualmente, o Brasil possui apenas dois antimicrobianos aprovados para uso na aquicultura: florfenicol e oxitetraciclina. A enrofloxacina (ENR) é um antibiótico largamente utilizado na medicina veterinária por apresentar elevado potencial de eficácia no tratamento de bacterioses. Porém, apesar de no Brasil ainda não ter uso regulamentado na piscicultura, muitos produtores acabam utilizando-a de forma ilícita, sendo adicionada à ração ou em banhos de imersão. Esses procedimentos de administração favorecem a perda do fármaco por meio da lixiviação, promovem a mudança do ecossistema aquático, além de prejudicar a saúde animal e do consumidor. Possíveis alternativas para facilitar a administração da ENR, minimizando os problemas causados no meio ambiente, são os revestimentos na ração, um dos mais antigos processos farmacêuticos ainda existentes e com grande aplicabilidade em diversos segmentos. Para a formação desses revestimentos, os polímeros utilizados precisam ser compatíveis com as características químicas e físico-químicas do fármaco, garantindo homogeneidade ao produto final e redução de perda do medicamento ao longo do tempo de administração da ração. Para tanto, faz-se necessário o revestimento da ração medicada seguida da avaliação das taxas de lixiviação, a fim de avaliar as perdas do fármaco para o ambiente. Para alcançar este objetivo, é necessária a disponibilidade de um método analítico devidamente validado que garanta a determinação do teor, antes e depois do processo de lixiviação da ração medicada. O método desenvolvido para quantificação da ENR na ração foi baseado na técnica de cromatografia líquida de alta eficiência com detector de arranjo de diodos (HPLC-DAD). O método foi validado considerando os seguintes parâmetros: linearidade, sensibilidade, seletividade, precisão intradia e interdias, exatidão, limite de detecção, limite de quantificação. Os resultados obtidos apresentaram conformidade com as recomendações dos guias de validação da Agência Nacional de Vigilância Sanitária (ANVISA, 2003) e do Ministério da Agricultura, Pecuária e Abastecimento (MAPA, 2010), indicando que o método é apropriado para a determinação de ENR na ração medicada. O revestimento da ração medicada tanto com 0,5 % quanto com 2,0 % de polivinilpirrolidona (PVP-K30) reduziu a taxa de lixiviação da ENR na ração para a água, porém essa taxa de redução depende significativamente (p<0,05) da temperatura e do tempo de permanência da ração na água / Abstract: Fish farming in Brazil has grown significantly over the past 20 years, reflected by increased production at high stocking densities. With the intensification of aquaculture, the emergence of outbreaks caused by various etiological agents becomes increasingly frequent, including the bacterial diseases. To combat the agents responsible for those diseases, many antibiotics are used illicitly. Nonetheless, in addition to the possibility of no effectiveness during treatment, they can induce lethality to the animals and cause environmental damage. Currently, Brazil has only two antimicrobials approved for use in aquaculture: florfenicol and oxytetracycline. Enrofloxacin (ENR) is an antibiotic widely used in veterinary medicine for presenting a high potential for efficacy in treating bacterial diseases. However, although in Brazil it is not yet regulated for use in fish farming, many farmers use it unlawfully, being added to the feed or by immersion baths. These procedures favor the drug loss through leaching from the feed, induce changes at the aquatic ecosystem, and endanger consumer and animal health. Possible alternatives to facilitate the administration of ENR, minimizing the problems caused in the environment are the feed coating, one of the oldest processes still exist with great applicability in several pharmaceutical segments. For the coating, polymers must be compatible with the chemical end physic-chemical characteristics of the drug, ensuring homogeneity of the final product and reduction of drug loss over time of feed administration. For this purpose, after coating the medicated feed becomes necessary to evaluate the leaching rate of the drug from the feed. To accomplish this it is required to develop and validate an analytical method that guarantees the determination of the drug content, before and after the leaching process of the medicated feed. The method for quantification of ENR in the feed was based on the technique of high performance liquid chromatography with diode array detector (HPLC-DAD). The method was validated considering the following parameters: linearity, sensitivity, selectivity, intra-day and inter-day precision, accuracy, detection and quantification limits. The results showed compliance with the recommendations from the validation guide of the National Agency for Sanitary Surveillance (ANVISA, 2003) and the Ministry of Agriculture, Livestock and Supply (MAPA, 2010), indicating that the method is suitable for the ENR determination on the medicated feed. The coating of the medicated feed with both: 0.5% and 2.0% polivinilpirrolydone (PVP-K30) reduced the leaching rate of the ENR from the feed to the water. However, the leaching rate reduction depends significantly (p<0.05) on the water temperature, as well as on the time residence of the feed in the water / Mestrado / Ciência de Alimentos / Mestra em Ciência de Alimentos

Ph.D. (Zoology) / Please refer to full text to view abstract

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / One of the pillars for optimizing cultured fish handling is stress reduction, and sedatives and anesthetics are tools usually employed in order to reach such goal. However, these drugs may cause physiological changes that can be deleterious to the animal if surpassing a physiological threshold. In this context, the current work investigated the use of a substance of natural origin, the essential oil (EO) of Aloysia triphylla, as well as of two synthetic drugs, tricaine methanesulfonate (MS222) and propofol, in silver catfish (Rhamdia quelen). The trials involved anesthesia (EO and MS222), for application in intensive or invasive manipulations, and sedation (propofol), to be used in procedures such as fish transport. Analyses of the effects of MS222, the prototypical fish anesthetic, and of the EO of A. triphylla showed that anesthesia with the naturally occurring substance presented more benefits for it prevented lipoperoxidation and limited cortisol secretion and ionic loss, although induction and recovery times were shorter with the traditional drug. Propofol as sedative for up to 12 hours did not increase cortisol secretion and alterations observed in hematological, biochemical and hydromineral indexes were limited. Moreover, assessment of gill morphology indicated that ionregulation and ventilation were not affected by propofol, while oxidative stress markers evidenced absence of peroxidative damage in vital organs, brain and liver, due to induction of some components of the antioxidant system, specially the enzyme superoxide dismutase, in the presence of the drug. These findings indicate that the EO of A. triphylla and propofol represent promising alternatives to be used in Brazilian fish culture, since anesthetics routinely applied in fish in other countries, such as MS222, are not commercially available in Brazil. In addition, the performance of MS222 was inferior when compared to that of the EO, which demonstrates that short induction and recovery periods do not necessarily mean less physiological burden. Studies as the ones described in this work contribute to welfare preservation of captive animal since possible actions to reduce stress are suggested. / Um dos pilares para a otimização do manejo de peixes cativos é a minimização do estresse, sendo os sedativos e anestésicos ferramentas habitualmente empregadas para obtenção deste objetivo. Entretanto, estes fármacos podem causar alterações que eventualmente se tornam deletérias ao animal se ultrapassarem o limite fisiológico. Neste contexto, o presente trabalho investigou o uso de uma substância de origem natural, o óleo essencial (OE) de Aloysia triphylla, e de dois anestésicos sintéticos, o metanosulfonato de tricaína (MS222) e o propofol, em jundiás (Rhamdia quelen). Os testes incluíram anestesia (OE e MS222), para uso em manipulações intensas ou invasivas, e sedação (propofol), para uso em procedimentos como o transporte. Análises dos efeitos do MS222, o protótipo de anestésico para peixes, e do OE de A. triphylla demonstraram que anestesia com a substância natural apresentou maiores benefícios por evitar a lipoperoxidação e limitar a secreção de cortisol e a perda de íons, apesar de os tempos de indução e recuperação terem sido mais curtos com o anestésico tradicional. O propofol como sedativo por até 12 horas não aumentou a liberação de cortisol e as alterações observadas em índices hematológicos, bioquímicos e hidrominerais foram limitadas. Ainda, a avaliação da morfologia branquial indicou que ionorregulação e ventilação não foram afetadas pelo propofol, enquanto que marcadores de estresse oxidativo evidenciaram a ausência de dano peroxidativo em órgãos vitais, encéfalo e fígado, devido à indução de alguns componentes do sistema de defesa antioxidante, especialmente da enzima superóxido dismutase, na presença do fármaco. Estes resultados indicam que o OE de A. triphylla e o propofol representam alternativas promissoras para uso na piscicultura brasileira, uma vez que anestésicos rotineiramente administrados a peixes em outros países, como o MS222, não estão disponíveis para compra no Brasil. Além disso, o desempenho do MS222 foi inferior àquele do OE, o que demonstra que tempos curtos de indução e recuperação não necessariamente significam menos prejuízo fisiológico. Estudos como os descritos neste trabalho contribuem para a preservação do bem-estar do animal mantido em cativeiro por sugerirem ações possíveis para redução do estresse.

Humic acid is an organic substance identified in black waters, used as growth promoter and confers protection against environmental contamination by metals. The objective of this study was to evaluate survival and growth of juvenile silver catfish Rhamdia quelen exposed to different concentrations of humic acid at acidic pH, observing the morphological effects in the gills and erythrocytes. In the first experiment, juveniles were exposed to two pH (5.5 and 6.5) with concentrations (0, 10, 25 and 50 mg.L-1) of humic acid (CAT: H1 0.675-2 Aldrich® - humic acid sodium salt) for 40 days. In the second study the histological and morphometric parameters of gills of juveniles exposed to these treatments were analyzed. The third study evaluated the effect of different pH (3.8, 4.0, 4.2 and 7.0) and the concentrations of humic acid previously described on survival and erythroid morphology of juvenile silver catfish. Silver catfish showed greater weight, length, biomass, feed intake, and specific growth rate when exposed to pH 6.5 without the presence of humic acid. The gills of silver catfish exposed to pH 5.5 at 50 mg.L-1 of humic acid presented higher filament length, width of the lamellae, thickness of the epithelium of gill filament, lower distance between the lamellae, cell proliferation and increase in chloride gill respiratory surface area GRSA. There was also proliferation of chloride cells and increase in chloride cells fractional area (CCFA) of juveniles exposed to pH 5.5 at 50 mg L-1 humic acid. Survival of juveniles was impaired at pH 3.8 and pH 4.0, and the higher the concentration of humic acid, the lower the survival. Silver catfish exposed to pH 7.0 showed higher erythrocyte are than those exposed to pH 3.8, 4.0 or 4.2. The presence of humic acid caused an opposite effect, increasing red cells diameter in fish exposed to higher concentrations (50 mg.L-1). No changes in plasma Na+, K+, but at pH 3.8 the plasma levels of Cl- were lower than at neutral pH and this effect was potentiated by the increase of humic acid levels. Thus, it is concluded that the presence of synthetic humic acid in water is harmful to the developing juvenile catfish, the higher the concentration of humic acid in water, the higher is the water barrier and blood-cell proliferation chloride, changing the gill morphology of juvenile catfish, hematological parameters of juvenile silver catfish are also altered by the presence of synthetic humic acid, which could compromise adaptation and survival of this species in acidic pH, the humic acid protects against the juvenile catfish ionorregulatórios negative effects of exposure the acidic pH. / O ácido húmico é uma substância orgânica identificada nas águas pretas, já utilizada como promotor de crescimento e que confere proteção contra a contaminação ambiental por metais. O objetivo deste estudo foi verificar a sobrevivência e o crescimento de juvenis de jundiá Rhamdia quelen em concentrações distintas de ácido húmico em pH ácido, observando os efeitos morfológicos nas brânquias e nos eritrócitos. No primeiro manuscrito, os juvenis foram expostos a dois pH (5,5 e 6,5) em concentrações (0, 10, 25 e 50 mg L-1) de ácido húmico, por 40 dias. No segundo manuscrito, foram analisados os aspectos histológicos e morfométricos das brânquias dos juvenis expostos a esses tratamentos ao final de 40 dias de experimento. O terceiro manuscrito avaliou a sobrevivência e o efeito na morfometria eritróide de juvenis de jundiá expostos a pH distintos (3,8; 4,0; 4,2 e 7,0) e nas concentrações de ácido húmico já citadas. Após ao experimento, os juvenis de jundiás apresentaram maior peso, comprimento, bioamassa, consumo de ração e taxa de crescimento específico quando expostos ao pH 6,5 sem a presença de ácido húmico. As brânquias dos jundiás expostos ao pH 5,5 em 50 mg L-1 de ácido húmico apresentaram maior comprimento dos filamentos, largura das lamelas e da espessura do epitélio do filamento branquial, menor distanciamento entre as lamelas, proliferação de células de cloreto e aumento na área de superfície respiratória GRSA. Também se verificou proliferação das células de cloreto e aumento na área fracional das células de cloreto (CCFA) dos juvenis expostos ao pH 5,5 em 50 mg L-1 de ácido húmico. A sobrevivência dos juvenis foi comprometida em pH 3,8 e pH 4,0, diminuindo esta sobrevivência em quanto maior foi a concentração de ácido húmico adicionado ao meio ambiente. Jundiás expostos ao pH 7,0 apresentavam área eritrocitária maior que os peixes expostos aos pH 3,8; 4,0 ou 4,2. Já a presença do ácido húmico causou um efeito contrário, fazendo com que os eritrócitos de peixes expostos às maiores concentrações (50 mg L-1) tivessem maiores diâmetros. Não há alteração nos níveis plasmáticos de Na+, K+, porém em pH 3.8 os níveis plasmáticos de Cl- foram menores que em pH neutro e esse efeito foi potencializado pelo aumento da concentração de ácido húmico. Assim, conclui-se que a presença do ácido húmico sintético na água é prejudicial para o desenvolvimento de juvenis de jundiá; quanto maior a concentração de ácido húmico na água, maior é a barreira águasangue e a proliferação de células de cloreto, alterando a morfologia branquial de juvenis de jundiá; os parâmetros hematimétricos de juvenis de jundiás também são alterados pela presença do ácido húmico sintético, podendo comprometer a adaptação e sobrevivência desta espécie em pH ácido; o ácido húmico protege juvenis de jundiá contra os efeitos ionorregulatórios negativos da exposição ao pH ácido.

INTRODUCTION: Estuaries have received considerable attention from biologists in southern Africa in the past thirty years. Professor J.H. Day and the Zoology Department of the University of Cape Town have undertaken ecological surveys of a large number of estuaries of a variety of types, laying the important groundwork for more detailed studies of single species or problems. Their studies showed that the fish populations of southern African estuaries consist mainly of marine species. Why and when these species enter or leave the estuaries and whether they grow or breed in them were not established. The only relatively detailed study of a fish in southern African estuaries was that of Talbot (1955) who investigated aspects of the growth, feeding and reproduction of Rhabdosargus globiceps (Cuvier). No quantitative information has been published on any of the fish species, perhaps due to the difficulty of obtaining such data; results such as population estimates, mortality rates and growth rates are particularly unreliable when the area being investigated is in direct contact with the sea. Studies relating to even a single species of fish are hampered by immigration and emigration between estuary and sea, which make the population continuously variable. The larger estuaries are also difficult to sample adequately, especially with regard to netting, except perhaps on a very large scale using expensive commercial equipment. Along the southern African coast many of the smaller estuaries with a limited catchment area are cut off from the sea for most of the year due to erratic rainfall and longshore drift of sand. These closed or 'blind' estuaries of south eastern Africa, of which there are at least thirty in the eastern Cape Province, provide excellent areas for studying estuarine fish populations which enter when the estuary is open to the sea, but become isolated once it closes. These fish which become cut off in closed estuaries are subject to a new series of conditions. They are exposed to the wider temperature and salinity fluctuations of an estuary and they are forced to utilise the food resources of the estuary. Additionally they may be subjected to predation from piscivorous birds, and those predatory fish which are also cut off in the estuary. These factors will affect the size, mortality, and growth rates of a fish population. Since the fish are isolated no recruitment from the sea can take place, and any increase in numbers would have to come from breeding within the estuary. It is inevitable that the most numerous species should receive attention first. Rhabdosargus holubi (Steindachner) (Synonomy : Sargus holubi Stndr, Austrosparus tricuspidens Smith, Rhabdosargus tricuspidens (Smith))(Plate 1) is one of the most abundant fish in the estuaries of the eastern Cape Province. According to Smith (1965) it is endemic to southern Africa, occurring from the Cape to Zululand, being most common between Mossel Bay and East London. It is largely replaced by Rhabdosargus sarba (Forskal) in the north of its range and by Rhabdosargus globiceps (Cuvier) in the south. Commonly called the 'flatty' or silver bream it is considered only as being of nuisance value by fishermen, seldom exceeding 30 cm in length. In this study the ecology of R.holubi was examined in relation to the closed West Kleinemond estuary which is a small 'blind' estuary typical of those found along the eastern Cape coast. The growth, mortality and population size of R.holubi in this estuary were investigated and linked where possible with predation and detailed studies into the tolerances, food, and feeding of the species. It was not known at the commencement of the study whether breeding could occur in estuaries, although Smith (1965) stated that R.holubi does breed in estuaries. During the course of the sampling programme in the West Kleinemond estuary, measurements of the growth and population structure of two other species of fish were recorded for comparison with R.holubi: the sparid Lithognathus lithognathus (Cuvier) (White Steenbras) and the piscivorous carangid Hypacanthas amia (L.) (Leervis or garrick). Laboratory studies on R.holubi were possible due to the fact that large numbers of this species could be caught in eastern Cape estuaries and transported to Grahamstown, where they could be maintained in captivity for up to four months in recirculating seawater aquaria. During the course of the study over 2000 fish were kept in captivity at different times for a variety of experiments. Another 2500 were preserved for gut analyses and lipid determinations, while over 5000 were captured, examined and released in the field.

The effect of dietary protein, protein and energy ratios, fish meal replacement by Soya bean meal and feeding frequency was investigated on the growth, feed efficiency and body composition, of juvenile dusky kob, Argyrosomus japonicus. The effect of dietary protein levels was investigated by comparing isocaloric diets containing 35, 40, 45 and 55% protein. Dietary protein inclusion level significantly affected specific growth rates, feed efficiency and body composition (in terms of fat deposition) and results show that a minimum of 45% and maximum of 52.3% dietary protein is optimal. The protein and energy requirements were investigated by comparing three protein levels (35,40 and 45%) with three lipid levels (6, 9 and 12%) in a 3x3 factorial design. A diet 45% protein and 9% lipid, with a P: E ratio of29 mglkJ and DE of 15.5 kJ/g resulted in an optimal specific growth rate (1.6± 0.2), feed efficiency (FCR= 1.7±0.44; PER= 1.36) and body composition for A. japonicus. To investigate the effect of partial fish meal replacement by Soya bean meal (SBM) in the diet, 20-50% of the protein from fish meal was substituted by protein from SBM, and were compared with a control diet containing only fish meal. No significant differences in the specific growth rates, feed efficiencies and the body composition were recorded for the fish fed the control diet and for fish fed the 20 and 30% SBM treatments. Results show that up to 30% of the protein from fish meal can be replaced with protein from SBM in the diet of this species. The effect of feeding frequency and gut evacuation time was investigated by comparing four feeding frequencies. Fish were fed to satiation either once, twice, three or four times a day. Feed intake was significantly affected by feeding frequency and fish fed 2, 3 and 4 meals a day ate significantly more food (p< 0.05) than the fish fed one meal a day. No significant differences (p> 0.05) in the specific growth rates, feed efficiencies and body composition were recorded for fish fed 2, 3 and 4 times a day. Feed intake was used to calculate an optimal daily ration and feeding two meals a day resulted in an optimal daily ration of 4% BW/day. A gut evacuation time of 7.25 hours indicates that fish fed twice a day probably had sufficient time to digest their food and evacuate their guts, resulting in the same daily feed intake as fish given 3 and 4 meals a day. Results conclude that under the present experimental conditions, a minimum daily ration of 4% BW/day, fed twice a day (in the morning and evening) is required for optimal growth (SGR= 1.33± 0.1), feed efficiency (FCR= 1.96± 0.4; PER= 1.44± 0.2) and body composition in juvenile dusky kob.

The lack of locally manufactured marine finfish diets motivated the current project, which aimed to develop a practical diet specifically formulated for dusky kob. The first growth trial investigated the effect of pellet texture (i.e. hard versus soft pellets) and the inclusion of an additional binder, test treatments were compared to two reference diets. There was no significant difference in weight gain between fish fed the hard or soft pellets (p=0.17), over nine weeks. The fish fed the local trout feed weighed significantly less than those fed the test diets (p=0.003). There was no significant difference in leaching rate amongst treatments (p=0.45). A hard pelleted diet without gelatin is recommended in the commercial culture of dusky kob. Pellets with different physical shapes were tested to determine the effect of shape on settling speeds. A square shaped pellet had a slower sinking rate compared to a round shaped pellet (p<0.0001). Juvenile dusky kob, held in cages, fed the square pellets grew significantly faster than the fish fed the round pellet, with a mean weight gain of 16.81 ± 0.45 g (p=0.018). A growth trial was used to optimize the protein to energy (PE) ratio by adjusting dietary protein and lipid levels. Fish fed the diets with high levels of protein (46 % protein) achieved the better growth rates (125 % weight gain) compared to the lower protein diets (92 % weight gain) (p<0.0001). There was no significant difference in total ammonia production (TAN) level for the 46 and 42 % protein diets (p=0.68). The overall performance of the prototype diet was investigated in a closed recirculating system. Growth and FCR of the fish fed the prototype diet was on a par to those fed the commercially available diet currently used in the local farming industry. There was no significant difference in the blood chemistry for fish held at increased stocking densities. The prototype diet is suitable for use in recirculating systems, as there were no negative effects on water quality parameters. This study has laid a foundation for the manufacture of a practical commercial dusky kob diet in South Africa.

This research reports on the determination of the effects of fish size and feed pellet size on the settling characteristics of Rainbow trout (Salmo gairdneri) culture, tank cleaning wastes. Flocculant particle settling curves (Type II) were developed from settling column analysis of cleaning wastes from 11-311 gram Rainbow trout fed a moist pellet diet (Oregon Moist Pellet ®). Four feed pellet sizes were investigated: 3/32, 1/8, 5/32 and 3/16 inch. Overall non-filterable residue removal curves and individual particle settling velocity distribution curves, derived from the Type II settling curve of each fish size and feed pellet size group, were compared. Slopes and y-intercepts of the linearized overall non-filterable residue removal curves and individual particle settling velocity distribution curves were compared using the Equality of Slope Test (S:SLTEST). Results of the test for a common regression equation indicated there were no significant differences in the proportional distribution of particle sizes within the cleaning wastes. Variations observed in the initial rates of removal within the overall non-filterable residue removal curves were considered insignificant Settling trials were pooled in order to obtain single curves, characterizing the overall solids removal rate and the individual particle settling velocity distribution of the waste solids. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

The hypothesis tested in this study is that the application of ozone to reuse aquaculture water provides more favorable conditions for hybrid striped bass at production levels. Evaluation of water quality in fish culture systems being treated with ozone was made during a production trial (1200 fish/14,OOO 1). Originally, a control and four ozonated systems with doses of 3, 13, 25, and 45 g O3/kg feed/day supported fish for experimentation but, due to mechanical failure, only the control, the 13 and 25 g O3/kg feed/day treatments completed the full 35 week study. On an equal feeding basis, concentrations of dissolved organic carbon (DOC), carbonaceous biochemical oxygen demand (CBODs), and chemical oxygen demand (COD) were lowest in the most heavily ozonated systems. Ozone increased the biodegradation of DOC. Total suspended solids, particle size and distributions were impacted by ozone's flocculating properties. The percentages of particles in the smallest size range, 5-20 microns, were greater in the control system than the ozonated systems during weeks of equal feeding rates. When feeding rates differed, the control system maintained a larger number total particles per kilogram of feed administered. The pH of the ozonated systems was lower than the control which favored the ionized (less toxic) form of ammonia. Enhanced biodegradation of organics in the ozonated systems may have increased carbon dioxide production and caused a decline in pH. Greater nitrification in the ozonated systems may have also decreased the pH. Higher total ammonia nitrogen (TAN) levels were produced in the control on an equal feeding basis. Average weekly TAN t unionized ammonia (NH3), nitrite and nitrate concentrations remained at acceptable levels across treatments and throughout the production trial. Overall, the major indication of improved system conditions due to ozone treatment was that fish raised in the ozonated systems fed steadily throughout the growth trial while the control system's culture experienced periods of reduced feeding. / Master of Science