LEVELS OF SOME HEAVY METALS IN MUSCLES AND LIVER

OF FRESHWATER FARMED FISH AT ABBASSA

Diaa A. Al-Kenawy* and Niema A.F. Aly**

*The WorldFish center, **Central Laboratory for Aquaculture Research, Abbassa, Abou-Hammad, Sharkia, 44662, Egypt.

Received 12/ 3/ 2015

Accepted 28/ 4/ 2015

Abstract

Fish samples were used to evaluate heavy metal pollution in some earthen fish ponds located at Central Laboratory for Aquaculture Research (CLAR), Abbassa, Abu-Hammad, Sharkia Governorate, Egypt. Concentrations of some heavy metals (cadmium (Cd), lead (Pb), cupper (Cu), iron (Fe), manganese (Mn), and zinc (Zn)) and calcium (Ca), were analyzed in fish tissues (muscle and liver)
using atomic absorption spectrophotometer. The levels of the tested metals in Nile tilapia (Oreochromis niloticus), striped mullet (Mugil cephalus), African catfish (Clarias gariepinus), common carp (Cyprinus
carpio), and silver carp (Hypophthalmichthys
molitix) were consistently higher in liver than in muscle tissues of all the five fish species. Calcium concentration was anomalously higher in the muscle tissue than liver of Nile tilapia, common carp and silver carp but not in African catfish and striped mullet. Muscle-liver ratios (MLRs) of the respective heavy metals ranged between 0.04 (Cu) and 0.73 (Ca) for Striped mullet, 0.06 (Cu) and 0.79 (Ca) for African catfish, 0.03 (Cd) and 1.53 (Ca) for silver carp, 0.02 (Pb) and 1.33 (Ca) for Nile tilapia, 0.11 (Cu) and 2.15 (Zn) for common carp. Interestingly, copper indicated least MLR in almost all the investigated fishes except in Nile tilapia and silver carp. Calcium showed the highest MLR in all fish species except in common carp. On the other hand, the cadmium/zinc ratios were higher in the liver than muscles of all fishes analyzed. The threshold contamination value for human dietary risk was however, not exceeded.

Key words: Heavy metals, freshwater fish, fish ponds, muscle-liver ratio.