Determination of protein, lipid, and mineral content of fish meat is necessary to ensure that it meets requirements for food regulations and commercial specifications. The objective of the present study was to determine the chemical composition ofOreochromis niloticus(L.), Nile tilapia, under three different ecosystems: (1) high pollution and high density ofEichhornia crassipes, that is, water hyacinth (Lake Chivero), (2) medium pollution and medium density of water hyacinth (Lake Manyame), and (3) low pollution and low density of water hyacinth (Lake Kariba). Dry matter, protein, lipids, and ash were evaluated by proximate analysis. Minerals were determined by atomic absorption spectrophotometry and pH was determined by a pH meter. Lake Kariba fish had the highest percentage of dry matter, protein, and ash. These qualities were correlated to low levels of pollutants and high oxygen content in the harvest waters. The phosphorus content of fish from Lake Chivero was very high, in tandem with phosphate levels in the harvest waters. In addition, water from Lake Chivero had an alkaline pH, high nitrate, and low oxygen content. The results suggest that effluent from sewage works and fertilizer industries caused pollution and proliferation of water hyacinth, contributing to pervasion of the chemical composition of fish.

Three forms of Encosternum delegorguei consumed in Nerumedzo community, Bikita, Zimbabwe were analysed for their nutritional composition. Protein, fat, ash and mineral content were determined for the preprocessed, well prepared and spoiled bugs. The proximate composition and minerals of the insects were determined using standard methods. One Way Analysis of Variance (ANOVA) was used in analyzing data. They were found to contain 30-36% protein; 51-53% fat and 1-1.5% ash respectively. Spoiled bugs contained the lowest protein content of 30.76±0.98% and highest amount of magnesium of 120±2.2 mg/100g while the preprocessed and well processed contained 110±2.5 mg/100g and 112±2.4 mg/100g respectively. Phosphorous was the most abundant in all forms with a value of 570-575 mg/100g. Calcium levels for all the three forms showed an overall mean of 85-89 mg/100g. Among the trace elements, iron was the most abundant (19-22 mg/100g). Roasting increased the protein, ash and magnesium content. The findings suggest the consumption of E. delegorguei is not only based on its cultural and medical roles claimed by the community, but also on the nutrients present.