This study was carried out to evaluate the value chain performance of the aquaculture feed sector in Egypt, in terms of value addition, employment and profitability. The strengths and weaknesses of each link of the value chain were assessed and appropriate upgrading, management and development strategies were suggested. Quantitative data were collected for each link in the value-chain through structured questionnaires that were drafted and distributed to the key players in the sector; 25 fish feed mills and 34 fish farms covering different geographical and production regions.
The current study was designed to optimize the dietary levels of Spirulina platensis in Oreochromis niloticus; this was tested via graded levels. Six isonitrogenous and isocaloric rations containing graded levels of dried spirulina 0, 5, 7.5, 10, 15 and 20 g/kg diet were fed separately to six equal groups of O. niloticus fingerlings for 3 months. Growth performance, non-specific immune parameters, tissue reactions and resistance of tilapias post challenge infection with Pseudomonas fluorescens were estimated monthly.
The effects of ditch size on growth and production of mono-sex tilapia, Oreochromis niloticus in rain fed concurrent rice–fish system were technically and economically evaluated for a period of 4 months. Three different ditch sizes were tried: 5%, 10% and 15% of the total cultivable rice field. It is concluded that rice–fish farming in a rain fed ecosystem of Bangladesh with medium ditch size and stocking density of 5000 ha-1 mono-sex tilapia can achieve better economic return.
It is proposed that the "recruitment pattern" routine of the ELEFAN II program can be modified to allow, in addition to length-frequency data, the use of "restructured" data files. An example, based on Oreochromis niloticus in Lake Itasy, Madagascar, is given to show that this results in recruitment patterns that have less temporal spread and hence better reflect the actual seasonality of recruitment.
Three discrete generations of GIFT fish (Nile tilapia strain, Oreochromis niloticus; a total of 10,065 fish with pedigree and phenotypic information) were tested in pond and cage culture environments to determine genotype by production environment interaction between both environments in Malaysia. Live weight (selected trait), standard length, body depth and width were recorded. A bivariate animal model was used to estimate variance and covariance components, whereby the homologous body traits in pond and cage environments were treated as genetically distinct traits.