An investigation into the dietary requirements of Oreochromis Mossambicus fry and the formulation and preparation of a dry food for use in aquaculture
- Authors: Thorpe, Peter Stuart
- Date: 1989
- Subjects: Cichlids , Tilapia -- Nutrition , Aquaculture
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5184 , http://hdl.handle.net/10962/d1001960 , Cichlids , Tilapia -- Nutrition , Aquaculture
- Description: The need for developing a dry feed which satisfied the nutrient requirements of Oreochromis mossambicus fry was identified. The spawning and grading techniques which resulted in a higher fecundity and ensured uniformity within and between samples of fry are discussed. Preparation techniques were developed which met the physical requirements of fry feeds. An analysis of the flesh and yolk sac fry for amino acid composition was undertaken. The initial test diet was based on these results, as well as on the natural feeding ecology of the species. Feeding trials were undertaken and growth responses monitored to determine the optimum levels of the various dietary components. A feed was developed which gave superior growth to that obtained with natural food organisms. This feed consisted of Torula yeast (47%), Weider Super Protein (44.39%), Vitamin supplement (0.45% - multivitamin), additional vitamin C supplement (0.16%), Spirulina (5%), and methionine supplement (3%). An optimum particle size range for O. mossambicus fry (between 5 & 25mm) was established at 125-200um. The fry should be fed the following feed ratios depending on age: 30.4% body weight/day up to day 5, 30.6% body weight/day up to day 10 and 25.1% body weight/day up to day 15. An optimum feeding frequency of 8/10hr day was recommended. A feed conversion ratio of 1.24:1 and a protein efficiency ratio of 0.682:1 was obtained. Digestable energy of the feed was determined at 16.1 kj/g feed. The established dry feed is suitable for use in commercial hatcheries, and as a formulation for further research on the intensive rearing of O. mossambicus fry.
- Full Text:
- Date Issued: 1989
- Authors: Thorpe, Peter Stuart
- Date: 1989
- Subjects: Cichlids , Tilapia -- Nutrition , Aquaculture
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5184 , http://hdl.handle.net/10962/d1001960 , Cichlids , Tilapia -- Nutrition , Aquaculture
- Description: The need for developing a dry feed which satisfied the nutrient requirements of Oreochromis mossambicus fry was identified. The spawning and grading techniques which resulted in a higher fecundity and ensured uniformity within and between samples of fry are discussed. Preparation techniques were developed which met the physical requirements of fry feeds. An analysis of the flesh and yolk sac fry for amino acid composition was undertaken. The initial test diet was based on these results, as well as on the natural feeding ecology of the species. Feeding trials were undertaken and growth responses monitored to determine the optimum levels of the various dietary components. A feed was developed which gave superior growth to that obtained with natural food organisms. This feed consisted of Torula yeast (47%), Weider Super Protein (44.39%), Vitamin supplement (0.45% - multivitamin), additional vitamin C supplement (0.16%), Spirulina (5%), and methionine supplement (3%). An optimum particle size range for O. mossambicus fry (between 5 & 25mm) was established at 125-200um. The fry should be fed the following feed ratios depending on age: 30.4% body weight/day up to day 5, 30.6% body weight/day up to day 10 and 25.1% body weight/day up to day 15. An optimum feeding frequency of 8/10hr day was recommended. A feed conversion ratio of 1.24:1 and a protein efficiency ratio of 0.682:1 was obtained. Digestable energy of the feed was determined at 16.1 kj/g feed. The established dry feed is suitable for use in commercial hatcheries, and as a formulation for further research on the intensive rearing of O. mossambicus fry.
- Full Text:
- Date Issued: 1989
The effect of the pesticide, endosulfan, on hepatic cytochrome P-450, liver and gill ultrastructure, and selected haematological parameters of Oreochromis Mossambicus (Peters, 1852) (Pisces : Cichlidae)
- Authors: Quick, Arthur Joseph Rex
- Date: 1986
- Subjects: Pesticides , Mozambique tilapia , Cichlids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5195 , http://hdl.handle.net/10962/d1001971 , Pesticides , Mozambique tilapia , Cichlids
- Description: Two possible ways in which fish may acclimate to prolonged exposure· to sublethal levels of endosulfan were investigated: induction of the hepatic monooxygenase system and changes in haematology. These studies also involved an examination of the ultrastructure of liver and gill tissue. Endosulfan caused none of the characteristic phenobarbital-type inductive effects on the liver of Oreochromis mossambicus. There was no increase in cytochrome P-450 levels, microsomal protein or hepatosomatic index. The reasons for the lack of induction are discussed. The effect of endosulfan on the following haematological parameters was determined: haemoglobin, erythrocyte count, microhaematocrit, mean erythrocyte volume and mean erythrocyte haemoglobin concentration. The only effect was an increase in erythrocyte count. The value of changes in haematological parameters as indicators of pollutioninduced anemia in the field is discussed. No changes in gill ultrastructure were noted although electron micrographs of liver tissue showed lesions in hepatocytes. The diagnostic value of pollution-induced pathological changes on cell ultrastructure are discussed. Recommendations are made with regard to future large scale application of pesticides on or near large water bodies
- Full Text:
- Date Issued: 1986
- Authors: Quick, Arthur Joseph Rex
- Date: 1986
- Subjects: Pesticides , Mozambique tilapia , Cichlids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5195 , http://hdl.handle.net/10962/d1001971 , Pesticides , Mozambique tilapia , Cichlids
- Description: Two possible ways in which fish may acclimate to prolonged exposure· to sublethal levels of endosulfan were investigated: induction of the hepatic monooxygenase system and changes in haematology. These studies also involved an examination of the ultrastructure of liver and gill tissue. Endosulfan caused none of the characteristic phenobarbital-type inductive effects on the liver of Oreochromis mossambicus. There was no increase in cytochrome P-450 levels, microsomal protein or hepatosomatic index. The reasons for the lack of induction are discussed. The effect of endosulfan on the following haematological parameters was determined: haemoglobin, erythrocyte count, microhaematocrit, mean erythrocyte volume and mean erythrocyte haemoglobin concentration. The only effect was an increase in erythrocyte count. The value of changes in haematological parameters as indicators of pollutioninduced anemia in the field is discussed. No changes in gill ultrastructure were noted although electron micrographs of liver tissue showed lesions in hepatocytes. The diagnostic value of pollution-induced pathological changes on cell ultrastructure are discussed. Recommendations are made with regard to future large scale application of pesticides on or near large water bodies
- Full Text:
- Date Issued: 1986
Astatotilapia tweddlei, a new species of fluviatile haplochromine cichlid fish from lakes Chilwa and Chiuta, Malawi, with zoogeographical notes
- Jackson, P B N (Peter Brian Neville), J.L.B. Smith Institute of Ichthyology
- Authors: Jackson, P B N (Peter Brian Neville) , J.L.B. Smith Institute of Ichthyology
- Date: 1985-06
- Subjects: Cichlids , Fishes -- Malawi
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/70202 , vital:29633 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 38 , Recent collecting in the Malawi lakes Chilwa and Chiuta has revealed a new haplochromine cichlid fish, Astatotilapia tweddlei, which is described and illustrated. It is distinguished from most members of this genus by an elongate, rounded caudal fin. Although having a distinctly different colour pattern and more slender pharyngeal bone, it shows a greater similarity to A. paludinosa, known only from the Malagarasi Swamp 1200 km to the north in the Zaire ichthyofaunal province, than it does to members of this genus from the closely adjacent Zambezi province from which this wetland system, in the East Coast province is separated by only some 50 km.
- Full Text:
- Date Issued: 1985-06
- Authors: Jackson, P B N (Peter Brian Neville) , J.L.B. Smith Institute of Ichthyology
- Date: 1985-06
- Subjects: Cichlids , Fishes -- Malawi
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/70202 , vital:29633 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 38 , Recent collecting in the Malawi lakes Chilwa and Chiuta has revealed a new haplochromine cichlid fish, Astatotilapia tweddlei, which is described and illustrated. It is distinguished from most members of this genus by an elongate, rounded caudal fin. Although having a distinctly different colour pattern and more slender pharyngeal bone, it shows a greater similarity to A. paludinosa, known only from the Malagarasi Swamp 1200 km to the north in the Zaire ichthyofaunal province, than it does to members of this genus from the closely adjacent Zambezi province from which this wetland system, in the East Coast province is separated by only some 50 km.
- Full Text:
- Date Issued: 1985-06
A new species of Tropheus (Pisces: Cichlidae) from Lake Tanganyika
- Axelrod, G S (Glen S.), Rhodes University. J.L.B. Smith Institute of Ichthyology
- Authors: Axelrod, G S (Glen S.) , Rhodes University. J.L.B. Smith Institute of Ichthyology
- Date: 1977-11
- Subjects: Cichlids , Tropheus , Freshwater fishes -- Tanganyika, Lake
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/69803 , vital:29581 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 17 , Tropheus polli, a sp. nov. (Pisces: Cichlidae) from Lake Tanganyika, is described and compared with T. moorii Boulenger 1898, T. annectens Boulenger 1900, T. duboisi Marlier 1959, T. brichardi Nelissen & Thys 1975, and T. moorii kasabae Nelissen 1977. Included are detailed morphometric data with a figure and colour plate, a lower pharyngeal bone description with electron micrograph scans, and a type locality map.
- Full Text:
- Date Issued: 1977-11
- Authors: Axelrod, G S (Glen S.) , Rhodes University. J.L.B. Smith Institute of Ichthyology
- Date: 1977-11
- Subjects: Cichlids , Tropheus , Freshwater fishes -- Tanganyika, Lake
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/69803 , vital:29581 , Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB)) Periodicals Margaret Smith Library (South African Institute for Aquatic Biodiversity (SAIAB))
- Description: Online version of original print edition of the Special Publication of the J.L.B. Smith Institute of Ichthyology; No. 17 , Tropheus polli, a sp. nov. (Pisces: Cichlidae) from Lake Tanganyika, is described and compared with T. moorii Boulenger 1898, T. annectens Boulenger 1900, T. duboisi Marlier 1959, T. brichardi Nelissen & Thys 1975, and T. moorii kasabae Nelissen 1977. Included are detailed morphometric data with a figure and colour plate, a lower pharyngeal bone description with electron micrograph scans, and a type locality map.
- Full Text:
- Date Issued: 1977-11
A contribution to the biology of Tilapia mossambica Peters in Lake Sibaya, South Africa
- Authors: Bruton, Michael N
- Date: 1973
- Subjects: Cichlids , Tilapia , Mozambique tilapia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5839 , http://hdl.handle.net/10962/d1009950 , Cichlids , Tilapia , Mozambique tilapia
- Description: An account is given of some aspects of the biology of Tilapia mossambica Peters in Lake Sibaya, South Africa. Previous work on Tilapia in Lake Sibaya is reviewed. Apart from brief gillnet surveys, which recorded the species' presence, no research on T. mossambica had been performed at Lake Sibaya before the two-year study of Minshull who collected data on food preferences, depth distribution of juveniles and breeding biology of adults. The main physiographical features of the lake are outlined. Lake Sibaya is a warm shallow coastal lake with extensive shallow terraces in the littoral which shelve abruptly into underwater valleys. The substrate is predominantly sandy. Aquatic macrophytes are generally restricted to water 1-7 m deep. Adult fishes (over 8 cm SL) are usually absent from water deeper than 12 m and shallower than 0.5 m, whereas juveniles may occur at all depths, and fry only in very shallow water. T. mossambica inhabits the littoral in the warm and transition periods (August to April) but moves into deep water in the cool season (May to July). Exposed and sheltered shallow areas are utilised for different purposes by adult fishes, the former for nesting, and the latter for feeding and mouth-brooding. Habitat selection by males was governed by nest site selection. Habitat Nests were most common in sheltered, sparsely vegetated littoral and sublittoral areas, but also present in well-vegetated sheltered areas. Breeding females preferred sheltered littoral areas but ventured onto the terrace to release the young. Juvenile and fry T. mossambica inhabited shallow exposed shores with a temperature gradient which reversed diurnally. The breeding, shoaling and feeding behaviour of T. mossambica is described, and integrated with data on T. mossambica from other systems. The breeding season spans seven months. Shoaling takes place in shallow water probably as a means of protection. T. mossambica is an omnivorous feeder relying largely on diatoms. The main predator is probably the barbel Clarias gariepinus, but avian predators may be more important. A method whereby the time of formation of rings on the scales of T. mossambica is described. The fishes were found to reach maturity after one year at a length of about 8 cm in females, and after two years at 10 cm in males. The breeding population had a standard length mode of 14 cm (females) and 17 cm (males). The maximum final size was about 24 cm SL. An estimate of the standing crop for fishes in the littoral and subiittoral areas of the eastern and southern shores of the south basin is given. The data were derived from a mark and recapture The biology of T. mossambica in Lake Sibaya as revealed by the present study is discussed with reference to data on the same and similar species in other systems. The utilis ation of the available resources in the lake by T. mossambica is commented upon, and reference is made to the significance of stunting, and the import ance of the retention of generalised characters for the successful habitation of the cyclically-renewed habitat of the littoral. Precocious breeding in T. mossambica is regarded as a functional adaptation which increases the proportion of fishes small enough to utilise the rich food resources in shallow water.
- Full Text:
- Date Issued: 1973
- Authors: Bruton, Michael N
- Date: 1973
- Subjects: Cichlids , Tilapia , Mozambique tilapia
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5839 , http://hdl.handle.net/10962/d1009950 , Cichlids , Tilapia , Mozambique tilapia
- Description: An account is given of some aspects of the biology of Tilapia mossambica Peters in Lake Sibaya, South Africa. Previous work on Tilapia in Lake Sibaya is reviewed. Apart from brief gillnet surveys, which recorded the species' presence, no research on T. mossambica had been performed at Lake Sibaya before the two-year study of Minshull who collected data on food preferences, depth distribution of juveniles and breeding biology of adults. The main physiographical features of the lake are outlined. Lake Sibaya is a warm shallow coastal lake with extensive shallow terraces in the littoral which shelve abruptly into underwater valleys. The substrate is predominantly sandy. Aquatic macrophytes are generally restricted to water 1-7 m deep. Adult fishes (over 8 cm SL) are usually absent from water deeper than 12 m and shallower than 0.5 m, whereas juveniles may occur at all depths, and fry only in very shallow water. T. mossambica inhabits the littoral in the warm and transition periods (August to April) but moves into deep water in the cool season (May to July). Exposed and sheltered shallow areas are utilised for different purposes by adult fishes, the former for nesting, and the latter for feeding and mouth-brooding. Habitat selection by males was governed by nest site selection. Habitat Nests were most common in sheltered, sparsely vegetated littoral and sublittoral areas, but also present in well-vegetated sheltered areas. Breeding females preferred sheltered littoral areas but ventured onto the terrace to release the young. Juvenile and fry T. mossambica inhabited shallow exposed shores with a temperature gradient which reversed diurnally. The breeding, shoaling and feeding behaviour of T. mossambica is described, and integrated with data on T. mossambica from other systems. The breeding season spans seven months. Shoaling takes place in shallow water probably as a means of protection. T. mossambica is an omnivorous feeder relying largely on diatoms. The main predator is probably the barbel Clarias gariepinus, but avian predators may be more important. A method whereby the time of formation of rings on the scales of T. mossambica is described. The fishes were found to reach maturity after one year at a length of about 8 cm in females, and after two years at 10 cm in males. The breeding population had a standard length mode of 14 cm (females) and 17 cm (males). The maximum final size was about 24 cm SL. An estimate of the standing crop for fishes in the littoral and subiittoral areas of the eastern and southern shores of the south basin is given. The data were derived from a mark and recapture The biology of T. mossambica in Lake Sibaya as revealed by the present study is discussed with reference to data on the same and similar species in other systems. The utilis ation of the available resources in the lake by T. mossambica is commented upon, and reference is made to the significance of stunting, and the import ance of the retention of generalised characters for the successful habitation of the cyclically-renewed habitat of the littoral. Precocious breeding in T. mossambica is regarded as a functional adaptation which increases the proportion of fishes small enough to utilise the rich food resources in shallow water.
- Full Text:
- Date Issued: 1973
Some aspects of the effect of temperature on the respiratory and cardiac activities of the Cichlid Teleost Tilapia mossambica
- Authors: Josman, V
- Date: 1971
- Subjects: Fishes -- Effect of temperature on , Cichlids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5859 , http://hdl.handle.net/10962/d1012613
- Description: The importance of the cichlid teleost Tilapia mossambica as a protein source, coupled with its remarkable adaptability, has resulted in its introduction into many water systems throughout the tropical, sub-tropical and even temperate regions of the world. However, its successful exploitation of these waters is dependent very largely upon the value of minimum temperatures and their duration. For e.g. Long et al (1961) has drawn attention to the tremendous mortalities of T. mossambica that occur in shallow water bodies during the precipitous temperature decreases that accompany the winter monsoons in Vietnam and other eastern countries, even at temperatures as high as 14 or 16º C. Coehe (1967) does not recommend stocking with T. mossambica where temperatures are not above 14º C all the time. Ailanson et al (1962) conclude, after an experimental study, that low temperatures (13º C or lower) in South African highveld dams in winter are certainly an important factor in the extensive mortalities of T. mossambica that have been reported from these dams. Jubb (1961) also reports that this species is often killed during a severe winter in Rhodesia. Intro., p.1.
- Full Text:
- Date Issued: 1971
- Authors: Josman, V
- Date: 1971
- Subjects: Fishes -- Effect of temperature on , Cichlids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5859 , http://hdl.handle.net/10962/d1012613
- Description: The importance of the cichlid teleost Tilapia mossambica as a protein source, coupled with its remarkable adaptability, has resulted in its introduction into many water systems throughout the tropical, sub-tropical and even temperate regions of the world. However, its successful exploitation of these waters is dependent very largely upon the value of minimum temperatures and their duration. For e.g. Long et al (1961) has drawn attention to the tremendous mortalities of T. mossambica that occur in shallow water bodies during the precipitous temperature decreases that accompany the winter monsoons in Vietnam and other eastern countries, even at temperatures as high as 14 or 16º C. Coehe (1967) does not recommend stocking with T. mossambica where temperatures are not above 14º C all the time. Ailanson et al (1962) conclude, after an experimental study, that low temperatures (13º C or lower) in South African highveld dams in winter are certainly an important factor in the extensive mortalities of T. mossambica that have been reported from these dams. Jubb (1961) also reports that this species is often killed during a severe winter in Rhodesia. Intro., p.1.
- Full Text:
- Date Issued: 1971
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