Since the most of the fish consumed in the Kathmandu Valley are brought from commercial farms
in the Terai region of Nepal and some from India, the quality characteristics of such fishes are
foremost importance. Therefore, this study was carried out to provide the information on heavy
metal concentrations in the muscles of nine commercial fish species available in the markets of
Kathmandu Valley and to make people aware of the possible health risk associated with their
consumption. The concentrations of Lead (Pb), Arsenic (As), Cadmium (Cd), Zinc (Zn), Manganese
(Mn) and Chromium (Cr) were determined in the muscles of Catla catla, Pampus species, Puntius
chola, Eutropiichthys vacha, Pampus chinensis, Clarias batrachus, Labeo bata, Labeo rohita and
Mystus tengara. The levels of heavy metals were measured by atomic absorption spectrophotometry
after digestion of the samples using the heating digester. There were significant variations among
heavy metal levels in the muscles of the nine fish species, and no fish types had the highest levels of
more than two metals. First, three maximum mean concentrations of potentially toxic elements were
found 16.75 µg/g in Puntius chola, 12.13 µg/g in Eutropiichthys vacha, 11.63 µg/g in Catla catla for
lead; 1.45 µg/g in Puntius chola, 1.35 µg/g in Pampus species and 1.15 µg/g in Mystus tengara for
cadmium; and 1.01 µg/g in Eutropiichthys vacha, 0.76 µg/g in Pampus species, 0.65 µg/g in Pampus
chinensis for arsenic. Similarly, first three maximum mean concentrations of essential elements
were found 9.88 µg/g in Puntius chola, 7.63 µg/g in Clarias batrachus, 5.75 µg/g in Catla catla
for manganese; 89.75 µg/g in Clarias batrachus, 68.37 µg/g in Catla catla, 65.38 µg/g in Puntius
chola for zinc; and 14.63 µg/g in Clarias batrachus, 13.13 µg/g in Pampus species, 10.50 µg/g in
Labeo rohita for chromium. The results showed that the heavy metals were found to be higher mean
concentrations in the sample of Puntius chola, then in Catla catla, Pampus species and Clarias
batrachus respectively; whereas they were found to be lower mean concentration in Eutropiichthys
vacha, Pampus chinensis, Labeo bata, Labeo rohita and Mystus tengara correspondingly. The
total mean concentration of manganese, lead and chromium in all fish samples was found to be
higher than the limits permitted by the Food and Agriculture Organization (FAO) of the United
Nations/World Health Organization (WHO) whereas the mean concentration of zinc and cadmium
was found lower than the permissible level of FAO/WHO, National Health and Medical Research
Council (NHMRC) and Malaysian Food and Regulations (MFR) guidelines. Similarly, the total
mean concentration of cadmium was also found to be lower than the permissible level of Centre
for Environment, Fisheries and Aquaculture Science (CEFAS), Boletin Oficial del Estado (BOE),
NHMRC, European Community Regulation (EU) and MRF in all fish samples. The total mean level
of lead was found lower than BOE guidelines. Likewise, the total mean level of chromium was
found slightly exceeded over limits suggested by the European Economic Community (EEC). This
study showed that all the fish samples examined were found to contain some heavy metals above the
FAO/WHO standard levels which may cause problems on the human health. At last, this research
work suggests that fish consumers should always bear in mind that standards cannot provide a
margin of safety when they are not enforced locall