A Study on Factors Affecting Fish Production from Certain Fish Farms in the Delta

Abstract

The present study was conducted to investigate factors affecting fish culture in some fish farms that use different sources of water (fresh water, agriculture drainage and sewage wastewater). The culture water was subjected to physical, chemical and biological analysis. Also, bacteriological examination (total bacterial count and total coliform) and heavy metal residues (iron, copper, zinc, cadmium and lead) were determined in both water and fish muscle. The physico-chemical properties of water showed highly significant difference among the different sources of the culture water. The sewage-fed ponds revealed the highest density of phytoplankton and zooplankton followed by agriculture drainage fish ponds, whereas fresh water ponds had the lowest density. The muscle, gills and liver tissues of fish samples reared in sewage fish ponds had highest levels of heavy metal residues and bacterial load (in muscle) followed by agriculture drainage ponds then fresh water ponds. - The growth rate and total yield of Oreochromis niloticus and Mugil cephaius reared in sewage-fed ponds and agriculture drainage ponds were higher than that reared in freshwater ponds. From the obtained results, it can be concluded that conditions at sewage-fed ponds and agriculture drainage fish ponds were appropriate for fish rearing, though fish are not safe for human consumption. The bacterial and heavy metal studies revealed that there is a public health hazard associated with sewage wastewater and agriculture drainage re-use in aquaculture, as the quality of fish did not comply with the standard levels recommended by WHO and USEPA. Potential adverse health effects in such applications could be avoided if the wastewater is sufficiently treated before use.