Animal Waste and Agro-by-Products: Valuable Resources for Producing Fish at Low Costs in Sub-Saharan Countries

Animal and crop production throughout the world generate high amounts of wastes or by-products annually that may possess added value compounds with high functionality. These wastes and by-products may cause negative environmental impacts and significant expenses if not well managed and or controlled. Much of these wastes and by-products is valuable and cheaper source of potentially functional compounds such as proteins, lipids, starch, micronutrients, bioactive compounds, and dietary fibbers. In aquaculture, feed is expensive, and the existing body of literature has shown that animal manure and its extracts can be successfully incorporated into fishpond to increase fish production at a low cost. In addition, crop residues such as rice bran, maize bran, and seed cakes are commonly used as pond inputs in small-scale aquaculture. Animal waste and crop residues are added in a fishpond that filter-feeding fish can use directly as feed, and these may form a major proportion of the detritus in the pond. These resources also stimulate the growth of phytoplankton that are rich in protein and are the basis of the food web that can support the growth of a range of herbivorous and omnivorous fish. Therefore, technically, wastes are used as direct feed, a source of minerals for autotrophic production and a source of organic matter for heterotrophic production. In this context, animal manure and crop residues have been used to provide great opportunities to improve food security. The purpose of this review is to project the potential of animal waste and agro-by-products as a sustainable alternative as aquaculture inputs to reduce poverty, malnutrition, and hunger in developing countries

Effect of Salinity on the Survival and Growth of Rufiji Tilapia (Oreochromis urolepis urolepis) Fry

AbstractSurvival and growth of Rufiji tilapia (Oreochromis urolepis urolepis) fry were determined under controlled salinity conditions of 5, 15, 25 and 35 ppt for 56 days. Experiments were carried out in 12 concrete tanks of 1 m3 volume each with three replicates for each treatment. Data was recorded at fourteen days intervals where weight measurements (g) of fry were recorded to the nearest 0.01 g. One Way Analysis of Variance (ANOVA) was used for data analysis. Results showed significant differences in the final body weight, specific growth rate, weight gain and daily growth rate at different salinity levels. The fry reared at a salinity of 25 ppt had the highest final body weight, specific growth rate, weight gain and daily growth rate, while the lowest was recorded at the salinity of 5 ppt. There was no significant difference in survival rate among the fry reared at different salinity levels. Dissolved oxygen (DO) was significantly different at different levels of salinity but temperature and pH showed no significant differences. The results suggest that under proper management, Rufiji tilapia can be farmed in brackish and sea water by coastal communities along the coast.