Nutritional and environmental toxicological investigations on fish farms in Fayoum governorate, Egypt

This study was carried out in two fish farms in EL-Fayoum Governorate to investigate water quality, evaluate the effect of chemical fertilizers and artificial diet on the performance and feed efficiency of Oreochromis niloticus and Mugil cephalus, and determine pesticide residues in water and reared fish. Average values of water temperature in fish farms and water source ranged between 25.6 and 30.6°C. The highest values of dissolved oxygen were observed during April while the lowest values were found in June and July. There was a negative relationship between water temperature and dissolved oxygen, a positive relationship was found between temperature and water salinity. The highest values of weight gain [270.90, 269.20g], specific growth rate [1.15, 1.16], feed consumption [240.60, 270.48g] and feed conversion ratio [0.89, 1.01] of O. niloticus and M. cephalus, respectively were found in fish fed on artificial feed and reared in fertilized ponds when compared to fish fed on artificial diet only or reared in fertilized ponds without supplementary feed. The pesticide residues of chlorpyrifos ethyl and fenpropathrin were detected in water at mean levels ranged 0.10 - 0.25 mg/I. Both fish species contained fenitrothion residues at values [0.525 mg/ kg and 0.255 mg/kg for O. niloticus and M. cephalus, respectively] which are higher than permissible limits. Although the residues of fenitrothion and carbaryl were not detected in water, they were found in both fish species which could be attributed to the ability of these pesticides to bioacumulate in the aquatic organisms

comparative study of fish cultured in sewage-fed farms of lake manzala and fish grown in wastewater stabilization pond system in Suez, Egypt

When fish are raised in sewage effluents, toxic chemicals present in the wastes may pose a threat to the humans who consume the fish and in addition may adversely affect the fish. Thus study compares the loadings of some organochlorine pesticides and heavy metals in two fish species cultured in one of the fish farms of lake Manzala that receives large quantities of untreated sewage with the fish grown in the wastewater stabilization pond system of the Suez Experimental Station [SES]. The residue levels of the organochlorine pesticides p.p' DDT and its metabolites represented the highest levels of organochlorines in all fish samples from either sites followed by Lindane and BHC. The proportion of p,p' DDE was the dominant compound followed by p,p' DDD and p,p' DDT in all first samples. However, residues of organochlorine pesticides in fish from Manzala sewage- fed farm were much higher than the fish grown in fish ponds of SES. Also the concentration levels of the heavy metals lead [pb], copper [Cu], zinc [Zn] and cadmium [Cd] in fish from Manzala sewage- fed farm were significantly higher than those in fish from the wastewater stabilization pond system of SES. The concentration levels of lead [Pb] and cadmium [Cd] in fish from Manzala sewage-fed farm exceeded the international permissible limits. On the other hand, fish raised in the wastewater stabilization pond system of SES were chemically safe for human or other consumption. The residue and concentration levels of organochlorines and heavy metals were far below the international permissible and safe limits